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February SNV AEG Field Trip - Frenchman Mountain, the Great Unconformity, and Rainbow Gardens
Saturday, February 12, 2022
Category: Chapters

Saturday, February 12, 2022 -  AEG Field Trip to Frenchman Mountain, the Great Unconformity, and Rainbow Gardens  

Led by Dr. Steve Rowland, Geoscience Professor Emeritus, UNLV

The Southern Nevada Chapter of the Association of Environmental and Engineering Geologists is having a field trip to the Frenchman Mountain area Saturday, February 12 to see the Frenchman Mountain Fault, the Great Unconformity, and the Thumb Member of the Horse Spring Formation in Rainbow Gardens. All of these features in the Frenchman Mountain Block have been transported here from the Gold Butte area by lystric extensional faulting and strike-slip faulting along the Las Vegas Valley Shear Zone.

 The Frenchman Mountain Fault has the most potential for a large earthquake in Las Vegas as it dips west beneath the center of the valley. The Great Unconformity is the contact between the Precambrian and Cambrian, perhaps the most significant geological contact on the planet. No need to hike down to the bottom of the Grand Canyon to see it. It is just off Lake Mead Boulevard. (Las Vegas has everything!) The third stop is in Rainbow Gardens, also along the road. Here we will examine a debris flow that occurred before the Frenchman Mountain Block was transported to the Las Vegas Valley. Dr. Rowland will discuss the discovery of this phenomenon well before the advent of satellite photography(see below)


Google Earth image of the Lake Mead region.  On this field trip we will examine evidence that the Frenchman Mountain/Rainbow Gardens structural block was translated 60 km from it's pre-early-Miocene position on top of the Gold Butte block to its present position via kinetically coupled strike-slip and low-angle normal faults. 

We will be meeting at 0900, Saturday, February 12 at the outcrop of the Frenchman Mountain Fault. It is located on Owens Avenue, east of Hollywood Boulevard, and up the slope from the intersection of Owens and Los Feliz. Owens is located ½ mile south of Lake Mead Boulevard.Bring lunch and water and dress for the weather. The field trip should be over in the early afternoon.

This field trip is free to all members and students members. There is a fee of $20 for non-members and $10 for student non-members, which will be collected in the field. Please bring exact cash or a check made out to the AEG Southern Nevada Chapter. (Or join AEG and attend for free.)

Support your profession by joining the AEG.  Here is the link to our chapter website for you to join AEG and attend our monthly field trips for free and our dinner meetings for the members’ price:  Join AEG (aegsnv.org)

To register for the field trip contact Jeremy Holst. Indicate whether or not you are a member or student member.

([email protected])  

For questions and more information about the field trip contact Steve Rowland at [email protected] or Nick Saines at [email protected].

See you in the field!