by Tiffany Chisum
SOCORRO, N.M., July 9, 2007 – The two newest issues of New Mexico Geology are now available. One focuses on sediment and its ability to explain ancient (300 million years ago) climates and events as well as the more recent history (from about 800,000 years ago to the present) of the Rio Grande. The other focuses on fossils found at the White Mesa mine.
The February issue of New Mexico Geology has an article on how the sequence stratigraphy of the Abo member in the Robledo and Doña Ana Mountains near Las Cruces may reveal ancient climates and events. Glacial cycles resulting in dramatic changes in sea level are demonstrated to have been common. This article argues that in addition to glacial cycles, climate changes and tectonics may also have influenced the types of strata found in these areas.
Another article explains how the sediment found along the edge of the Rio Grande valley in the central Albuquerque basin reveals former channels of the Rio Grande. By studying the fluvial deposits in this area, scientists are able to explain how the position of the Rio Grande has changed over time and how those changes are differentiated between San Felipe Pueblo and Los Lunas.
The May issue of New Mexico Geology offers the second half of an article that began in the August 2006 issue. That article, “Tectonic development of late Pleistocene (Rancholabrean) animal-trapping fissures in the Middle Jurassic Todilto Formation, north-central New Mexico,” covered the examination and discussion of the formation of fissures that captured large mammals and then preserved their fossils. The article published in the May issue covers the examination and discussion of the fossils found in those fissures.
The article explains that the fossil–containing fissures were discovered at White Mesa mine on Zia Pueblo in Sandoval County. At least 44 fissures were discovered within 100 meters of the fossil site, but only three of those fissures contained fossils. Of the fossils found, three of the species are of extinct Pleistocene-age large mammals (stilt-legged horse, camel, and bison) and two are living species (mule deer and pocket gopher). The discovery of these bones allows scientists to postulate the habitat in the vicinity during late Pleistocene geologic time, as well as how the animals became trapped and their bones preserved. The specimens from the White Mesa mine are curated in the vertebrate paleontology collection of the New Mexico Museum of Natural History; however, they remain the property of Zia Pueblo. The skeletons of a bison and a camel, both extinct species, will eventually be placed on display in the Ice Age Hall at the museum. The fossils were determined by radiocarbon dating methods to be around 13,000 years old.
The May issue also has an article covering the 2007 New Mexico Science and Engineering Fair and lists the students who received the “Excellence in Geoscience” award, as well as information on their projects. The abstracts and poster sessions from the New Mexico Geological Society spring meeting are also provided.
An article on the flooding of the Rio Puerco is also presented. It explains what kind of river the Rio Puerco is and how it contributes to the Rio Grande. The article discusses the flooding of the river and provides pictures of the Rio Puerco during flooding and normal conditions.
Both issues of New Mexico Geology also contain a Service News section, as well as notices about upcoming geologic meetings.
New Mexico Geology is published quarterly by the New Mexico Bureau of Geology and Mineral Resources (NMBGMR), a research and service division of New Mexico Tech. A subscription to the award-winning journal costs $12.00 per year or $22.00 for two years. Individual issues may be purchased for $3.50 per issue. Back issues may be purchased for $12.00 per volume (year); individual articles can be downloaded for free at http://geoinfo.nmt.edu/publications/periodicals/nmg/home.html.
For more information about New Mexico Geology, or any other NMBGMR publication, write to the Bureau Publication Office, New Mexico Tech, 801 Leroy Place, Socorro, NM 87801, call 505.835.5145 or 505.835.5490, or visit the NMBGMR website at http://geoinfo.nmt.edu.