EXHIBIT 23.1 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in this Current Report on Form 8-K/A under the Securities Exchange Act of 1934 of St. Mary Land & Exploration Company dated February 25, 2000 of our report on King Ranch Energy, Inc. and subsidiaries dated March 2, 1999 and contained in Registration Statement 333-85537 of St. Mary Land & Exploration Company on Form S-4 under the Securities Act of 1933 insofar as such report relates to the financial statements of King Ranch Energy, Inc. and subsidiaries for the year ended December 31, 1998. /s/ DELOITTE & TOUCHE LLP DELOITTE & TOUCHE LLP Houston, Texas February 25, 2000