Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico. Free Downloads NMGS has decided to make peer-reviewed papers from our Fall Field Conference guidebooks available for free download. Non-members will have access to guidebook papers two years after publication. Members have access to all papers. This is in keeping with our mission of promoting interest, research, and cooperation regarding geology in New Mexico. However, guidebook sales represent a significant proportion of our operating budget. Therefore, only research papers are available for download. Road logs, mini-papers, maps, stratigraphic charts, and other selected content are available only in the printed guidebooks. Copyright Information Publications of the New Mexico Geological Society, printed and electronic, are protected by the copyright laws of the United States. No material from the NMGS website, or printed and electronic publications, may be reprinted or redistributed without NMGS permission. Contact us for permission to reprint portions of any of our publications. One printed copy of any materials from the NMGS website or our print and electronic publications may be made for individual use without our permission. Teachers and students may make unlimited copies for educational use. Any other use of these materials requires explicit permission. This page is intentionally left blank to maintain order of facing pages.

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The Oklahoma Panhandle and adjacent areas in Texas, Kansas, Colorado, and New Mexico have prospered because of the development of supplies of fresh water and of oil and gas. The Ogallala and, in places, Cretaceous rocks produce fresh water for irrigation, public supply, and domestic and stock use through approximately 9,000 irrigation and publicsupply wells and a large but undetermined number of other wells. Disposal of oilfield brine and other wastes into the Glorieta Sandstone is of concern to many local residents because of the possibility of pollution of the overlying freshwater aquifers, particularly the Ogallala Formation. Permits for 147 disposal wells into the Glorieta have been issued in this area. This report summarizes the data on geology, hydrology, and water development currently available to the U.S. Geological Survey. Geologic information indicates that, in the report area, the Glorieta Sandstone lies at depths ranging from about 500 to 1,600 feet below the base of the Ogallala Formation. The rocks between those two formations are of relatively impermeable types, but solution and removal of salt has resulted in collapse of the rocks in some places. Collapse and fracturing of the rocks could result in increased vertical permeability. This might result in movement of brine under hydrostatic head from the Glorieta Sandstone into overlying freshwater aquifers, in places where an upward hydraulic gradient exists or is created by an increase in pressure within the Glorieta. Abandoned or inadequately sealed boreholes also are possible conduits for such fluids. The mixing of water in the freshwater aquifers with brines injected into the Glorieta is not known to have occurred anywhere in the report area, but the information available is not adequate to show positively whether or not this may have occurred locally. Much additional information on the stratigraphy and hydrology-particularly, data on the potentiometric 1 surface of water in the Glorieta-needs to be collected and analyzed before conclusions can be drawn regarding the possibility of vertical movement of oilfield brines from the Glorieta to freshwater aquifers above.

Sedimentary rocks of Paleozoic age are present throughout the 25,000 square miles that comprises the Navajo and Hopi Indian Reservations, or Navajo country, in the south-central part of the Colorado Plateaus physiographic province. These rocks are exposed only in the Monument Valley, the Defiance Plateau, the Zuni Mountains, and the southwestern part of the reservations.Pre-Pennsylvanian Paleozoic rocks crop out only in the lower reaches of the canyon of the Little Colorado River, Grand Canyon, and Marble Canyon, but they have been penetrated in deep oil tests in Black Mesa basin and in the Four Corners area of Arizona, New Mexico, Utah, and Colorado. These rocks are represented by Cambrian, Devonian, and Mississippian strata and have a combined thickness of nearly 1,500 feet at the confluence of the Colorado and Little Colorado Rivers and 1,200 feet in the Four Corners area. They thin eastward and southeastward across the area and are absent in the southeastern part of the reservations.The lower boundary of the Cambrian is represented by an erosion surface in the Grand Canyon and in the adjoining part of the Navajo Indian Reservation. The hiatus between Precambrian and Cambrian deposition includes an unknown quantity of late Precambrian time, part of early Cambrian time in the Grand Canyon area, and considerably more of Cambrian time in areas to the east. In the Grand Canyon area, Cambrian rocks are designated as the Tonto Group and include, in ascending order, the Tapeats Sandstone, the Bright Angel Shale, and the Muav Limestone. Between 250 and 750 feet of Cambrian rocks is recognized in drill cuttings from oil tests in the Four Corners area. These rocks consist of a basal sandstone that grades upward through shale into limestone and dolomite and have been correlated with the Cambrian section in the Grand Canyon and the Cambrian strata of central Utah.Rocks of definite Ordovician and Silurian ages do not occur in the Navajo country.The Temple Butte Limestone of Devonian age is exposed discontinuously in the lower part of the canyon of the Little Colorado River and in Marble Canyon. Devonian rocks have also been recognized in oil tests in the northern and westcentral parts of the reservations. None are exposed in the Defiance Plateau.The Mississippian rocks are represented by the Redwall Limestone in the reservations. The Redwall is present in the subsurface, except near the Defiance Plateau and the Zuni Mountains in the southeastern part of the reservations.Pennsylvanian and Permian rocks are described in their principal exposures-in the southwestern part of the Navajo country, in the Defiance Plateau, and in Monument Valley. Although they are also exposed in the Zuni Mountains, the Pennsylvanian and Permian rocks in that area are discussed only briefly in this report. Thicknesses of these rocks are 2,000 feet near the mouth of the Little Colorado River, 1,100 feet in the Defiance Plateau, and 3,600 feet in Monument Valley. These rocks are assigned different names in each of their principal areas of outcrop.Th...

Obtaining a groundwater supply____________________________________ 53 Springs. ______________________________________________________ 53 Wells. _______________________________________________________ 58 Dug wells________________________________________________ 58 Drilled wells_____________ ________________________________ 58 Collection galleries.