Structural and geochemical constraints on the reassembly of disrupted mid-Miocene volcanoes in the Lake Mead-Eldorado Valley area of southern Nevada

Geology ◽  
1987 ◽  
Vol 15 (6) ◽  
pp. 553 ◽  
Author(s):  
Michael E. Weber ◽  
Eugene I. Smith
Water Policy ◽  
2014 ◽  
Vol 16 (4) ◽  
pp. 720-738 ◽  
Author(s):  
Mahesh Gautam ◽  
Kumud Acharya ◽  
Seth A. Shanahan

The Las Vegas Wash is a dynamic channel system that drains the Las Vegas Valley (3,950 km2) into Lake Mead and the lower Colorado River, which provides drinking water to southern California, Arizona, and southern Nevada. In the last few decades the Las Vegas Wash has undergone massive changes in terms of channel degradation and bank erosion followed by recovery and restoration efforts. The evolution of the Las Vegas Wash is interlinked with urbanization, water use, and wastewater discharge. This article reviews the historical dynamics of the Las Vegas Wash in the context of restoration: evaluates the ongoing activities in the Las Vegas Wash against an established framework and success criteria; summarizes lessons learned; and discusses challenges. The ongoing activities in the Las Vegas Wash differ from other regional restoration projects in that there is a lack of an appropriate historical reference to which restoration goals should be targeted. Keys to the success of the Las Vegas Wash restoration and management program appear to be strong interagency collaboration, funding availability, effective outreach and monitoring efforts, and adaptive management strategies based on pragmatic urban values. There is a potential for realignment of existing resources for more practical ecological restoration goals.


1998 ◽  
Vol 35 (5) ◽  
pp. 495-503 ◽  
Author(s):  
Stephen S Harlan ◽  
Ernest M Duebendorfer ◽  
Jack E Deibert

New 40Ar/39Ar dates on volcanic rocks interlayered with synextensional Miocene sedimentary rocks in the western Lake Mead area and southern end of the Las Vegas Range provide tight constraints on magmatism, basin formation, and extensional deformation in the Basin and Range province of southern Nevada. Vertical axis rotations associated with movement along the Las Vegas Valley shear zone occurred after 15.67 ± 0.10 Ma (2 sigma ), based on a 40Ar/39Ar date from a tuff in the Gass Peak formation in the southern Las Vegas Range. Basaltic magmatism in the western Lake Mead area began as early as 13.28 ± 0.09 Ma, based on a date from a basalt flow in the Lovell Wash Member of the Horse Spring Formation. Isotopic dating of a basalt from the volcanic rocks of Callville Mesa indicates that these rocks are as old as 11.41 ± 0.14 Ma, suggesting that volcanic activity began shortly after formation of the Boulder basin, the extensional basin in which the informally named red sandstone unit was deposited. The red sandstone unit is at least as old as 11.70 ± 0.08 Ma and contains megabreccia deposits younger than 12.93 ± 0.10 Ma. This result shows that formation of the Boulder basin was associated with development of topographic relief that was probably generated by movement along the Saddle Island low-angle normal fault. Stratal tilting associated with extension occurred both prior to and after 11.5 Ma.


1944 ◽  
Vol 9 (3) ◽  
pp. 330-332 ◽  
Author(s):  
Gordon C. Baldwin

A number of mescal knives have been found throughout the southwestern United States, but very few of these have been adequately described in print. As the use or non use of this distinctive type of implement may in the future be of aid in establishing cultural affiliations and migrations of peoples, a brief description of two of these unusual pieces is presented below.The first of these mescal knives came from a small cave, or rock shelter, located about three and one-half miles southeast of the former town of St. Thomas, Nevada, at the foot of Bitter Spring Wash, where the latter enters the Virgin River. This site is now forever covered beneath the waters of Lake Mead, backed up behind Boulder Dam. The cave was excavated in 1936 by Civilian Conservation Corps enrollees under the direction of Junior Foreman Fay Perkins and under the supervision of the National Park Service.


2001 ◽  
Vol 23 (8) ◽  
pp. 1255-1279 ◽  
Author(s):  
Tim F Wawrzyniec ◽  
John W Geissman ◽  
R.Ernest Anderson ◽  
Steve S Harlan ◽  
James Faulds

Sign in / Sign up

Export Citation Format

Share Document