EXHIBIT 10.19 [Letterhead of Morris, Laing, Evans, Brock & Kennedy, Chartered] August 21, 1997 Mr. Ken Smith Petroglyph Operating Company, Inc. P.O. Box 1839 Hutchinson, KS 67504-1839 Re: Hutch Realty, L.L.C. Lease on Office Building Dear Ken: Pursuant to our recent conversation, we have agreed that the lease dated April 7, 1994 between Hutch Realty, L.L.C. and Petroglyph Operating Company, Inc. Has been extended beyond its two-year primary term and one-year extension term for an additional one-year period beginning May 7, 1997 through May 6, 1998. The parties have agreed that the rent will remain the same at $2000 per month. If you have any questions, please feel free to give me a call. Sincerely, HUTCH REALTY, L.L.C. By The Lee Company, Managing Member By: /s/ A.J. Schwartz ---------------------------------------------------- A.J. Schwartz, Agent and Attorney AJS:se xc: Norb Schwartz