Information presented on hydrology of limestone and related rocks at the conferences of the Ground Water Branch at Mammoth Cave, Kentucky, March 27-31, 1956, and at Carlsbad, New Mexico, November 13-17, 1956. UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Water Resources Division Washington 25, D.C. In reply refer to: May 17, 1957 Code 4051 0001 GROUND WATER BRANCH MEMORANDUM NO. 57.37 To: District Chiefs and Staff Officials, Ground Water Branch From: Chief, Ground Water Branch, Washington, D.C. Subject: Information presented on hydrology of limestone and related rocks at the conferences of the Ground Water Branch at Mammoth Cave, Kentucky, March 27-31, 1956, and at Carlsbad, New Mexico, November 13-17, 1956. Ground Water Branch Memorandum No. 57.21 requested that each person presenting a paper or giving an informal talk at either the Mammoth Cave or Carlsbad submit, without illustrations, a report or paper covering his presentation. Also requested was a memorandum from each district describing the principal limestones and related rocks which are known to be aquifers in that district. The information on limestone and related rocks known to be aquifers is needed for each State to give a more complete picture of the geographic aspects of limestone hydrology. When the contributions are assembled for review and publication, not only will the papers presented at each conference be considered, but also the information provided by the memorandums describing the principal aquifers of limestone and related rocks in each district will be used to round out any discussion on the areal extent of limestone aquifers. As soon as the papers are assembled for internal use and review in the Branch, each contribution will have an opportunity to review his part and make such changes, additions, and revisions as appear advisable. At that time plans can be made of the first of a series of reports for publication, including illustrations, on the occurrence and movement of ground water, with some information on the chemical quality and quantity of water in different kinds of geologic terranes in the United States. It was requested that these papers and memorandums be submitted by April 1, 1957. As of this date, copies of some of the papers presented and a few of the memorandums discussing the limestone and related-rocks aquifers of the respective districts have not been received. This task should not be unduly burdensome. However, if you wish to contribute to this volume you should submit your part in the near future or let us know promptly how much additional time will be required. The next group of papers will be prepared on the hydrology of basalts after the field conference next September in Idaho. Approval has been obtained for a conference on the hydrology of alluvial deposits in the western States some time next year. Later, plans will be made for conferences on glacial deposits and other terranes. (s) A. N. Sayre Distribution: A, B, GS, GFO