<SEC-DOCUMENT>0000950123-11-079116.txt : 20110822
<SEC-HEADER>0000950123-11-079116.hdr.sgml : 20110822
<ACCEPTANCE-DATETIME>20110822161721
ACCESSION NUMBER:		0000950123-11-079116
CONFORMED SUBMISSION TYPE:	SC 13D/A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20110822
DATE AS OF CHANGE:		20110822
GROUP MEMBERS:		YORKTOWN VI ASSOCIATES LLC
GROUP MEMBERS:		YORKTOWN VI COMPANY LP

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			HALLADOR ENERGY CO
		CENTRAL INDEX KEY:			0000788965
		STANDARD INDUSTRIAL CLASSIFICATION:	BITUMINOUS COAL & LIGNITE MINING [1220]
		IRS NUMBER:				841014610
		STATE OF INCORPORATION:			CO
		FISCAL YEAR END:			1224

	FILING VALUES:
		FORM TYPE:		SC 13D/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-37955
		FILM NUMBER:		111050061

	BUSINESS ADDRESS:	
		STREET 1:		1660 LINCOLN ST STE 2700
		CITY:			DENVER
		STATE:			CO
		ZIP:			80264
		BUSINESS PHONE:		3038395505

	MAIL ADDRESS:	
		STREET 1:		1660 LINCOLN STREET
		STREET 2:		SUITE 2700
		CITY:			DENVER
		STATE:			CO
		ZIP:			80264

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HALLADOR PETROLEUM CO
		DATE OF NAME CHANGE:	19920703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KIMBARK OIL & GAS CO /CO/
		DATE OF NAME CHANGE:	19900102

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KIMBARK INC
		DATE OF NAME CHANGE:	19860624

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Yorktown Energy Partners VI LP
		CENTRAL INDEX KEY:			0001347504
		IRS NUMBER:				201384906
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13D/A

	BUSINESS ADDRESS:	
		STREET 1:		410 PARK AVENUE
		STREET 2:		19TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		212-515-2112

	MAIL ADDRESS:	
		STREET 1:		410 PARK AVENUE
		STREET 2:		19TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13D/A
<SEQUENCE>1
<FILENAME>d84305sc13dza.htm
<DESCRIPTION>SC 13D/A
<TEXT>
<HTML>
<HEAD>
<TITLE>sc13dza</TITLE>
</HEAD>
<BODY bgcolor="#FFFFFF">
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<DIV style="font-family: 'Times New Roman',Times,serif">



<DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
<DIV style="width: 100%; border-bottom: 1pt solid black; font-size: 1pt">&nbsp;</DIV>




<DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>SECURITIES AND EXCHANGE COMMISSION</B>
</DIV>

<DIV align="center" style="font-size: 12pt"><B>Washington, D.C. 20549</B>
</DIV>

<DIV align="center" style="font-size: 18pt; margin-top: 12pt"><B>Schedule&nbsp;13D</B>
</DIV>


<DIV align="center" style="font-size: 12pt; margin-top: 12pt"><B>Under the Securities Exchange Act of 1934<BR>
(Amendment No.&nbsp;2)*</B>
</DIV>

<DIV align="center" style="font-size: 24pt; margin-top: 12pt"><B>HALLADOR ENERGY COMPANY</B>
</DIV>

<DIV align="center" style="font-size: 10pt"><B>(Name of Issuer)</B></DIV>


<DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>Common Stock, par value $0.01 per share<BR>
(Title of Class of Securities)</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>406092205<BR>
(CUSIP Number)</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>W. Howard Keenan, Jr.<BR>
Yorktown Energy Partners VI, L.P.<BR>
410 Park Avenue<BR>
19th Floor<BR>
New York, New York 10022<BR>
(212)&nbsp;515-2112</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>Copies to:</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>Ann Marie Cowdrey<BR>
Thompson &#038; Knight LLP<BR>
One Arts Plaza</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 0pt"><B>1722 Routh Street, Suite&nbsp;1500<BR>
Dallas, Texas 75201-2533<BR>
(214)&nbsp;969-1700</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 0pt"><B>(Name, Address and Telephone Number of Person<BR>
Authorized to Receive Notices and Communications)</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 6pt"><B>August&nbsp;9, 2011</B></DIV>

<DIV align="center" style="font-size: 10pt; margin-top: 0pt"><B>(Date of Event which Requires Filing of this Statement)</B></DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">If the filing person has previously filed a statement on Schedule&nbsp;13G to report the acquisition
that is the subject of this Schedule&nbsp;13D, and is filing this schedule because of &#167;&#167; 240.13d-1(e),
240.13d-1(f) or 204.13d-1(g), check the following box. <FONT style="font-family: Wingdings">&#111;</FONT>
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">NOTE: Schedules filed in paper format shall include a signed original and five copies of the
schedule, including all exhibits. See &#167; 240.13d-7 for other parties to whom copies are to be sent.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">* The remainder of the cover page shall be filled out for a reporting person&#146;s initial filing on
this form with respect to the subject class of securities, and for any subsequent amendment
containing information which would alter disclosures provided in a prior cover page.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">The information required on the remainder of this cover page shall not be deemed to be &#147;filed&#148; for
the purpose of Section&nbsp;18 of the Securities Exchange Act of 1934 (&#147;Act&#148;) or otherwise subject to
the liabilities of that section of the Act but shall be subject to all other provisions of the Act
(however, <I>see </I>the Notes).
</DIV>


<DIV style="width: 100%; border-bottom: 1pt solid black; margin-top: 10pt; font-size: 1pt">&nbsp;</DIV>
<DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>





<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>

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<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>



<DIV style="font-family: 'Times New Roman',Times,serif">

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="20%">&nbsp;</TD>
<TD width="55%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="9%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="9%">&nbsp;</TD>
</TR>
<!-- End Table Head -->
<!-- Begin Table Body -->


<TR valign="bottom">
<TD valign="top" nowrap><DIV style="margin-left:0px; text-indent:-0px">CUSIP No.</DIV></TD>
<TD>&nbsp;</TD>
<TD align="center" valign="top"><DIV style="border: 1px solid #000000">406092205&nbsp;</DIV></TD>
<TD>&nbsp;</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<P>&nbsp;<DIV style="width: 100%; border: 1px solid black"><DIV align="center">

<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="1" width="100%">
<!-- Begin Table Head --><TR style="font-size: 1px">
<TD width="5%">&nbsp;</TD>
<TD width="1%" style="border-left: 1px solid #000000">&nbsp;</TD>
<TD width="5%">&nbsp;</TD>
<TD width="5%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="83%">&nbsp;</TD>
</TR>

<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
<TD valign="middle" align="center"><FONT style="font-size: 18pt"><B>1</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">NAMES OF REPORTING PERSONS<BR>
<BR>
YORKTOWN ENERGY PARTNERS VI, L.P.</TD>
</TR>
<TR valign="bottom">
<TD>&nbsp;</TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>2</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)<BR><BR></TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">(a)&nbsp;&nbsp;&nbsp;<FONT face="wingdings" size="2">&#111;</FONT>&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">(b)&nbsp;&nbsp;&nbsp;<FONT face="wingdings" size="2">&#111;</FONT>&nbsp;</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>3</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">SEC USE ONLY</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>4</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">SOURCE OF FUNDS (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="11" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="11" align="left">OO</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>5</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left"><FONT face="wingdings" size="2">&#111;</FONT></TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>6</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CITIZENSHIP OR PLACE OF ORGANIZATION</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">Delaware
</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>7</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SOLE VOTING POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">NUMBER OF</TD>
<TD>&nbsp;</TD>
<TD align="left">5,057,166</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">SHARES</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>8</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SHARED VOTING POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">BENEFICIALLY</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">OWNED BY</TD>
<TD>&nbsp;</TD>
<TD>0</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>


<TR valign="bottom">
<TD align="center" colspan="3">EACH</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>9</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SOLE DISPOSITIVE POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">REPORTING</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">PERSON</TD>
<TD>&nbsp;</TD>
<TD align="left">5,057,166</TD>
</TR>
<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">WITH</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>10</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SHARED DISPOSITIVE POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD align="left">0</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>11</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">5,057,166 (1)</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>12</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK IF THE AGGREGATE AMOUNT IN ROW (11)&nbsp;EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left"><FONT face="wingdings" size="2">&#111;</FONT>
</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>13</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">18.0&#37; (2)</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>14</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">PN</TD>
</TR>
<!-- End Table Body --></TABLE>
</DIV>
</DIV>


<DIV align="left">
<DIV style="font-size: 3pt; margin-top: 6pt; width: 18%; border-top: 0px solid #000000">&nbsp;</DIV>
</DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
<TR>
    <TD width="3%"></TD>
    <TD width="1%"></TD>
    <TD width="96%"></TD>
</TR>

<TR valign="top">
    <TD nowrap align="left">(1)</TD>
    <TD>&nbsp;</TD>
    <TD>Yorktown VI Company LP is the sole general partner of Yorktown Energy Partners VI, L.P.
Yorktown VI Associates LLC is the sole general partner of Yorktown VI Company LP. As a result,
Yorktown VI Associates LLC may be deemed to have the power to vote or direct the vote or to
dispose or direct the disposition of the shares owned by Yorktown Energy Partners VI, L.P.
Yorktown VI Company LP and Yorktown VI Associates LLC disclaim beneficial ownership of the
securities owned by Yorktown Energy Partners VI, L.P. in excess of their pecuniary interests
therein.</TD>
</TR>

<TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>

<TR valign="top">
    <TD nowrap align="left">(2)</TD>
    <TD>&nbsp;</TD>
    <TD>Based on 28,163,180 shares of the Common Stock of the Company issued and outstanding as of
August&nbsp;5, 2011, as set forth in the Company&#146;s quarterly report on Form 10-Q for the quarter
ended June&nbsp;30, 2011, filed with the Securities and Exchange Commission (the &#147;SEC&#148;) on August
5, 2011.</TD>
</TR>

</TABLE>


<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>

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<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">






<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="20%">&nbsp;</TD>
<TD width="55%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="9%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="9%">&nbsp;</TD>
</TR>
<!-- End Table Head -->
<!-- Begin Table Body -->


<TR valign="bottom">
<TD valign="top" nowrap><DIV style="margin-left:0px; text-indent:-0px">CUSIP No.</DIV></TD>
<TD>&nbsp;</TD>
<TD align="center" valign="top"><DIV style="border: 1px solid #000000">406092205&nbsp;</DIV></TD>
<TD>&nbsp;</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<P>&nbsp;<DIV style="width: 100%; border: 1px solid black"><DIV align="center">

<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="1" width="100%">
<!-- Begin Table Head --><TR style="font-size: 1px">
<TD width="5%">&nbsp;</TD>
<TD width="1%" style="border-left: 1px solid #000000">&nbsp;</TD>
<TD width="5%">&nbsp;</TD>
<TD width="5%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="83%">&nbsp;</TD>
</TR>

<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
<TD valign="middle" align="center"><FONT style="font-size: 18pt"><B>1</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">NAMES OF REPORTING PERSONS<BR>
<BR>
YORKTOWN VI COMPANY LP</TD>
</TR>
<TR valign="bottom">
<TD>&nbsp;</TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>2</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)<BR><BR></TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">(a)&nbsp;&nbsp;&nbsp;<FONT face="wingdings" size="2">&#111;</FONT>&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">(b)&nbsp;&nbsp;&nbsp;<FONT face="wingdings" size="2">&#111;</FONT>&nbsp;</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>3</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">SEC USE ONLY</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>4</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">SOURCE OF FUNDS (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="11" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="11" align="left">OO</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>5</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left"><FONT face="wingdings" size="2">&#111;</FONT></TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>6</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CITIZENSHIP OR PLACE OF ORGANIZATION</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">Delaware
</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>7</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SOLE VOTING POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">NUMBER OF</TD>
<TD>&nbsp;</TD>
<TD align="left">5,057,166</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">SHARES</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>8</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SHARED VOTING POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">BENEFICIALLY</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">OWNED BY</TD>
<TD>&nbsp;</TD>
<TD>0</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>


<TR valign="bottom">
<TD align="center" colspan="3">EACH</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>9</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SOLE DISPOSITIVE POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">REPORTING</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">PERSON</TD>
<TD>&nbsp;</TD>
<TD align="left">5,057,166</TD>
</TR>
<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">WITH</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>10</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SHARED DISPOSITIVE POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD align="left">0</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>11</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">5,057,166 (1)</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>12</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK IF THE AGGREGATE AMOUNT IN ROW (11)&nbsp;EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left"><FONT face="wingdings" size="2">&#111;</FONT>
</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>13</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">18.0&#37; (2)</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>14</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">PN</TD>
</TR>
<!-- End Table Body --></TABLE>
</DIV>
</DIV>



<DIV align="left">
<DIV style="font-size: 3pt; margin-top: 6pt; width: 18%; border-top: 0px solid #000000">&nbsp;</DIV>
</DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
<TR>
    <TD width="3%"></TD>
    <TD width="1%"></TD>
    <TD width="96%"></TD>
</TR>

<TR valign="top">
    <TD nowrap align="left">(1)</TD>
    <TD>&nbsp;</TD>
    <TD>Yorktown VI Company LP is the sole general partner of Yorktown Energy Partners VI, L.P.
Yorktown VI Associates LLC is the sole general partner of Yorktown VI Company LP. As a result,
Yorktown VI Associates LLC may be deemed to have the power to vote or direct the vote or to
dispose or direct the disposition of the shares owned by Yorktown Energy Partners VI, L.P.
Yorktown VI Company LP and Yorktown VI Associates LLC disclaim beneficial ownership of the
securities owned by Yorktown Energy Partners VI, L.P. in excess of their pecuniary interests
therein.</TD>
</TR>

<TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>

<TR valign="top">
    <TD nowrap align="left">(2)</TD>
    <TD>&nbsp;</TD>
    <TD>Based on 28,163,180 shares of the Common Stock of the Company issued and outstanding as of
August&nbsp;5, 2011, as set forth in the Company&#146;s quarterly report on Form 10-Q for the quarter
ended June&nbsp;30, 2011, filed with the SEC on August&nbsp;5, 2011.</TD>
</TR>

</TABLE>


<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">



<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="20%">&nbsp;</TD>
<TD width="55%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="9%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="9%">&nbsp;</TD>
</TR>
<!-- End Table Head -->
<!-- Begin Table Body -->


<TR valign="bottom">
<TD valign="top" nowrap><DIV style="margin-left:0px; text-indent:-0px">CUSIP No.</DIV></TD>
<TD>&nbsp;</TD>
<TD align="center" valign="top"><DIV style="border: 1px solid #000000">406092205&nbsp;</DIV></TD>
<TD>&nbsp;</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<P>&nbsp;<DIV style="width: 100%; border: 1px solid black"><DIV align="center">

<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="1" width="100%">
<!-- Begin Table Head --><TR style="font-size: 1px">
<TD width="5%">&nbsp;</TD>
<TD width="1%" style="border-left: 1px solid #000000">&nbsp;</TD>
<TD width="5%">&nbsp;</TD>
<TD width="5%">&nbsp;</TD>
<TD width="1%">&nbsp;</TD>
<TD width="83%">&nbsp;</TD>
</TR>

<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
<TD valign="middle" align="center"><FONT style="font-size: 18pt"><B>1</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">NAMES OF REPORTING PERSONS<BR>
<BR>
YORKTOWN VI ASSOCIATES LLC</TD>
</TR>
<TR valign="bottom">
<TD>&nbsp;</TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>2</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)<BR><BR></TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">(a)&nbsp;&nbsp;&nbsp;<FONT face="wingdings" size="2">&#111;</FONT>&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">(b)&nbsp;&nbsp;&nbsp;<FONT face="wingdings" size="2">&#111;</FONT>&nbsp;</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>3</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">SEC USE ONLY</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>4</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">SOURCE OF FUNDS (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="11" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="11" align="left">OO</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>5</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left"><FONT face="wingdings" size="2">&#111;</FONT></TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>6</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CITIZENSHIP OR PLACE OF ORGANIZATION</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">Delaware
</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>7</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SOLE VOTING POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">NUMBER OF</TD>
<TD>&nbsp;</TD>
<TD align="left">5,057,166</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">SHARES</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>8</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SHARED VOTING POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">BENEFICIALLY</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">OWNED BY</TD>
<TD>&nbsp;</TD>
<TD>0</TD>
</TR>

<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>


<TR valign="bottom">
<TD align="center" colspan="3">EACH</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>9</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SOLE DISPOSITIVE POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">REPORTING</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">PERSON</TD>
<TD>&nbsp;</TD>
<TD align="left">5,057,166</TD>
</TR>
<TR style="font-size: 1px">
<TD colspan="3">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000; border-left: 1px solid #000000; border-right: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
<TD align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD align="center" colspan="3">WITH</TD>
<TD valign="middle" align="center" rowspan="3" style="border-left: 1px solid #000000; border-right: 1px solid #000000"><FONT style="font-size: 18pt"><B>10</B></FONT></TD>
<TD>&nbsp;</TD>
<TD align="left">SHARED DISPOSITIVE POWER</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD>&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD align="center" colspan="3">&nbsp;</TD>
<TD>&nbsp;</TD>
<TD align="left">0</TD>
</TR>
<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>11</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">5,057,166 (1)</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>12</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">CHECK IF THE AGGREGATE AMOUNT IN ROW (11)&nbsp;EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left"><FONT face="wingdings" size="2">&#111;</FONT>
</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>13</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">18.0&#37; (2)</TD>
</TR>

<TR style="font-size: 1px">
<TD style="border-top: 1px solid #000000">&nbsp;</TD>
<TD style="border-left: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left" style="border-top: 1px solid #000000">&nbsp;</TD>
</TR>

<TR valign="bottom">
<TD valign="middle" align="center" rowspan="3"><FONT style="font-size: 18pt"><B>14</B></FONT></TD>
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">&nbsp;</TD>
</TR>
<TR valign="bottom">
<TD style="border-left: 1px solid #000000">&nbsp;</TD>
<TD colspan="4" align="left">OO</TD>
</TR>
<!-- End Table Body --></TABLE>
</DIV>
</DIV>



<DIV align="left">
<DIV style="font-size: 3pt; margin-top: 6pt; width: 18%; border-top: 0px solid #000000">&nbsp;</DIV>
</DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
<TR>
    <TD width="3%"></TD>
    <TD width="1%"></TD>
    <TD width="96%"></TD>
</TR>

<TR valign="top">
    <TD nowrap align="left">(1)</TD>
    <TD>&nbsp;</TD>
    <TD>Yorktown VI Company LP is the sole general partner of Yorktown Energy Partners VI, L.P.
Yorktown VI Associates LLC is the sole general partner of Yorktown VI Company LP. As a result,
Yorktown VI Associates LLC may be deemed to have the power to vote or direct the vote or to
dispose or direct the disposition of the shares owned by Yorktown Energy Partners VI, L.P.
Yorktown VI Company LP and Yorktown VI Associates LLC disclaim beneficial ownership of the
securities owned by Yorktown Energy Partners VI, L.P. in excess of their pecuniary interests
therein.</TD>
</TR>

<TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>

<TR valign="top">
    <TD nowrap align="left">(2)</TD>
    <TD>&nbsp;</TD>
    <TD>Based on 28,163,180 shares of the Common Stock of the Company issued and outstanding as of
August&nbsp;5, 2011, as set forth in the Company&#146;s quarterly report on Form 10-Q for the quarter
ended June&nbsp;30, 2011, filed with the SEC on August&nbsp;5, 2011.</TD>
</TR>

</TABLE>


<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">






<DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;This Amendment No.&nbsp;2 amends the Schedule&nbsp;13D with respect to the Common Stock of Hallador
Energy Company, a Colorado corporation formerly known as Hallador Petroleum Company (the
&#147;Company&#148;), previously filed by Yorktown Energy Partners VI, L.P., a Delaware limited partnership
(&#147;Yorktown&#148;), with the SEC on December&nbsp;30, 2005, as amended by Amendment No.&nbsp;1 filed with the SEC
on May&nbsp;24, 2011 (the &#147;Schedule&nbsp;13D&#148;). Capitalized terms used herein without definition shall have
the meanings given to such terms in the Schedule&nbsp;13D.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;5. Interest in Securities of the Issuer.</B>
</DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Subparagraphs a, b and c of Item&nbsp;5 in the Schedule&nbsp;13D are amended and restated in their
entirety by the following:
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a)&nbsp;Yorktown, the General Partner and the LLC beneficially own 5,057,166 shares of Common
Stock of the Company, representing 18.0% of the issued and outstanding shares of Common Stock of
the Company. All calculations made herein are made in accordance with Rule&nbsp;13d-3(d) of the
Securities Exchange Act of 1934, as amended, and based on 28,163,180 shares of Common Stock of the
Company issued and outstanding as of August&nbsp;5, 2011.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b)&nbsp;The General Partner is the sole general partner of Yorktown. The LLC is the sole general
partner of the General Partner. The LLC has the sole power to cause the General Partner to cause
Yorktown to vote or direct the vote or to dispose or direct the disposition of the shares owned by
Yorktown.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c)&nbsp;On August&nbsp;9, 2011, Yorktown distributed in-kind, on a pro rata basis and for no additional
consideration, in accordance with its limited partnership agreement, an aggregate of 750,000 shares
of Common Stock of the Company, to its limited and general partners (the &#147;Distribution&#148;). Upon the
consummation of the Distribution by Yorktown, the General Partner distributed in-kind, on a pro
rata basis and for no additional consideration, in accordance with its limited partnership
agreement, all 11,084 shares of Common Stock of the Company received in the Distribution to its
limited and general partners (the &#147;Subsequent Distribution&#148;). Upon the consummation of the
Subsequent Distribution by the General Partner, the LLC distributed in-kind, on a pro rata basis
and for no additional consideration, in accordance with its operating agreement, all 57 shares of
Common Stock of the Company received in the Subsequent Distribution to its members.
</DIV>

<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">

<DIV align="center" style="font-size: 10pt; margin-top: 18pt">SIGNATURES
</DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;After reasonable inquiry and to the best of my knowledge and belief, I certify that the
information set forth in this statement is true, complete and correct.
</DIV>
<DIV align="left" style="font-size: 10pt; margin-top: 6pt">Date: August&nbsp;22, 2011
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">YORKTOWN ENERGY PARTNERS VI, L.P.
</DIV>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="40%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="50%">&nbsp;</TD>
</TR>
<TR></TR>
<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top">By:</TD>
    <TD>&nbsp;</TD>
    <TD colspan="5" valign="top" align="left">Yorktown VI Company LP,<BR>
its general partner</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom"><!-- Blank Space -->
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">By:</TD>
    <TD>&nbsp;</TD>
    <TD colspan="3" valign="top" align="left">Yorktown VI Associates LLC,<BR>
its general partner</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom"><!-- Blank Space -->
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">By:
</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">/s/ Peter A. Leidel
<DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
Peter A. Leidel, Managing Member
</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 12pt">YORKTOWN VI COMPANY LP
</DIV>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="35%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="50%">&nbsp;</TD>
</TR>
<TR></TR>
<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top">By:</TD>
    <TD>&nbsp;</TD>
    <TD colspan="3" valign="top" align="left">Yorktown VI Associates LLC,<BR>
its general partner</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom"><!-- Blank Space -->
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">By:
</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">/s/ Peter A. Leidel
<DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
Peter A. Leidel, Managing Member
</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 12pt">YORKTOWN VI ASSOCIATES LLC
</DIV>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="30%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="50%">&nbsp;</TD>
</TR>
<TR></TR>
<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">By:
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">/s/ Peter A. Leidel
<DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
Peter A. Leidel, Managing Member
</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>



<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>


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</HTML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
