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You are here: Home / Geology of the River Mountains

Geology of the River Mountains

River Mountain Loop Trail

Volcanoes?

This phrase will certainly get the attention of many, particularly those who are not familiar with the geology of the River Mountains. This certainly explains why they are so rugged!

The River Mountains are composed of tilted and faulted mid-Miocene (15 to 12 million years old) andesite and dacite lava flows. Two volcanoes, the source of most of the lava, have been identified in the River Mountains. *

Strato Volcano

Volcano cross-section

Stratovolcano cross section – USGS file photo

The first, located just north of Boulder city, is a stratovolcano surrounded by numerous domes. Stratovolcanoes are cone-shaped features composed of lava flows interbedded with abundant agglomerate and breccia that formed from explosive eruptions. The surrounding domes formed by the eruption of very sticky lava such as dacite, which erupted to the surface but did not flow. Lava formed a low spine or a dome that quickly crumbled to a ring of debris about the dome.

Volcano with lava flow.

This could have been River Mountains 14-million years ago. The birth of a mountain range.

Shield Volcano

The second volcano, located in the northern part of the River Mountains, is a shield volcano – a broad volcano composed of basaltic and andesitic lavas similar to those erupting today on the island of Hawaii.

Both volcanos have been tilted, cut by numerous faults, and broken into numerous parts producing a jigsaw pattern of rocks that is now very difficult to recognize.

The photo below is of a cinder cone just a mile north and east of the River Mountains and can be seen from the trail between mile-marker 12 and mile-marker 14. Locally it is called “Lava Butte.”

Volcanic cinder cone, Henderson, NV.

Lave Butte, a volcanic cinder cone just north of the River Mountain Loop Trail.

* Reference material from Nevada Bureau of Mines and Geology Special Publication #16, “Geologic tours in the Las Vegas area.”

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River Mountains Loop Trail
2 weeks ago
River Mountains Loop Trail

Update: Closure at RR Pass due to storm damage impacting concrete at railroad tracks.

Henderson is working with UPRR and the Boulder City Railroad Museum to make this repair as soon as possible.
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River Mountains Loop Trail
2 weeks ago
River Mountains Loop Trail
Hello All,

The City of Henderson is  temporarily re-routing trail traffic around the railroad tracks near Railroad Pass Casino. We dont have a timetable for this closure yet. 

Updates coming soon on the re-opening of this trail section.

Hello All,

The City of Henderson is temporarily re-routing trail traffic around the railroad tracks near Railroad Pass Casino. We don't have a timetable for this closure yet.

Updates coming soon on the re-opening of this trail section.
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15 CommentsComment on Facebook

It’ll be like this till next year or so .

Had a employee from Railroad museum, train is running but is being stop half down, it is not going pass Railroad Hotel and Casino he sad the track was damaged from Hilary and monsoon rain we had

Where does the trail reroute for this section?

I biked this today and there was no closure?!?!

Lisa Lohmann we will have remember this when we plan our long ride

For your safety = the government is all knowing and you must comply because you know no better!

Great, I’m usually hauling ass there, only to find a barricade 3 seconds till I hit them if I’m watching closely

Part of the F1 race construction?

Steve Burchell

There’s no easy “re-routing” once you’re at this point….

anything fun in henderson, the city wants to tax you to use.

Someone I know biked this section today from the ped bridge over the 11 to BC and said the trail was clear of all the dirt that was on the trail a week ago.

Rode by the Railroad Pass today, no problem. Is it still closed elsewhere?

Mattchew Fisherino

The resurfacing that was slated to begin back in April HAS BEGUN! Someone I know rode the RMLT early morning Monday the 18th and said there were roadwork crews busy repairing cracks and applying blacktop, so please abide by the trail closure signs on the northern section of the trail unless you enjoy riding through fresh tar. BTW, the gates at the RR Casino crossing have been moved out of the way and there appears to be nothing going on there in the way of repairs. Also, the entire trail has been cleared of all gravel and debris from the recent rains so thanks to the City of Henderson for dealing with that. The attached trail closure map that was put online last March now actually applies.

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River Mountains Loop Trail
3 weeks ago
River Mountains Loop Trail
Thank you John Day for cleaning storm debris off of the RMLT!

Thank you John Day for cleaning storm debris off of the RMLT! ... See MoreSee Less

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Thanks John and all that keep our trail clean! Your hard work is greatly appreciated!!

There are some great people in this world!!!

Awesome. We encountered some rough patches on Saturday morning.

Your a legend!! Thank you sir

Wow! What a mess, thanks for clearing all that. I loved riding that trail when I lived in Vegas🚴‍♀️

Thank you...so much!!

You can do the Beltway Trail when you are finished. LOL. All your hard work is greatly appreciated by the cycling community. Thank you.

We have an amazing group of “trail gnomes” in our mountain bike community who put in significant hours to maintain trails throughout the year that are my inspiration to contribute to the biking culture in Henderson, Las Vegas, and Boulder City.

Awesome my friend 🤙🏽

🙌🙌🙌

Clap clap for him .. thank you so much

Thank you

Huge thanks!

I’ve been there 3x on that trail it’s amazing. we start at the railroad casino, thanks for your outstanding support 👏🏻👏🏻

Thanks much. Does anyone know if it needs cleaning anywhere else?? I have free time tomorrow.

Thank you!!!

Thank you John Day!

Thank you!

Thank you!!

Thank you 😊

thanks!

thank you so much, i saw you Saturday but i had to find my husband who turned around, thanks again, appreciate you!!!

Thank you John!

Thank you sir! Greatly appreciated! Kerry Jo Mitchell

Robert Jr Samano

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