GARDEN OF THE GODS

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GEOLOGY

COLORADO U.S.A

 

The Towers and Spires in the Garden Of The Gods Park are part of a Back Thrust fault system, which is when a Thrust Fault has opposite Vergence to the main Thrust System. The Colorado Front range is visible from the park, the mountain range is both an erosional feature and a Tectonic one. 

The Larminide Orogeny was a slow mountain building event that affected the Colorado Springs area and took part in the formation of the Garden Of The Gods around 70-40 million years ago.

South of Fountain creek the towers of orange Lyons Sandstone are cut off abruptly due to the Ute Pass Fault. The Rampart Range fault that sits opposite of the Ute Pass Fault, is part of a Faulted Monocline system that resides along the base of the Front Range but is hidden under layers of sediment. The famous rock formations in the park are the result of the overturned vertical limb of the Rampart Range Fault.   

The rock layers are younger towards the East and have been offset from several small faults that reside in the park. There are at least 3 Eastward dipping reverse faults that cut across the Lyons Sandstone fins. 

Garden Of The Gods viewed from the visitors center

LYONS SANDSTONE

The fins and spires in the Garden Of The Gods are formed from the Lyons Sandstone. The Sandstone was once a Coastal Dune System during the Permian age 299-251 million years ago.

 

The sand grains are cemented together by silica and tiny grains of Hematite which is why the thin spires can sit at 90 degrees and be so resistant to weathering. The Lyons Formation is roughly 700 ft thick and is divided into 3 different members, the lowest member is red sandstone while the middle member is Fountain-like Arkosic conglomerate, the upper member is a white/red colour which has been strongly-crossbedded.

 

The Fountain Formation lies below the Lyons Sandstone, it's around 4050 ft thick. The Fountain Formation is a deep red mudstone/conglomerate. The rock strata in the formation tilt less steeply and form mushroom-like pedestals from differential erosion.

 

Poor sorting and heavy crossbedding indicate that the materials that make up the Fountain Formation weren't transported very far from the source. The formation is believed to have once been a series of alluvial fan deposits from the eroding ancestral Rocky Mountains.  

Upper member of the Lyons Formation

Lyons Sandstone

FAULTING

There are 2 major faults that have shaped the Garden Of The Gods region, the Ute Pass Fault and the Rampart Range Fault. Both faults are close to each other but do not converge with each other. 

UTE PASS FAULT

The Ute pass fault has a slip rate of less than 0.2 mm/yr, the Ute Pass Fault Zone defines West and Southwest margins of the Rampart Range. 

The fault zone is mostly defined by a series of 5 northwest-trending faults that lie West of Colorado Springs. The faults are parallel to the base of the Southwest flank of the Rampart Range and towards Fountain Creek. The fault terminates in a series of splay faults at the southern end of the Eastern flank of the Front Range. Splay faults are branching synthetic faults which are located near the termination of a major fault.

The Ute Pass Fault is visible through bedrock scraps which are discontinuous throughout the southern trace of the Fault, the northeast trace is lacking visible bedrock scrap altogether.

 

The Quaternary fault scraps within rockfall deposits are known evidence of fault activity during the quaternary age. Late fault movement in the Cenozoic is strongly supported along most of the fault as well.  

RAMPART RANGE FAULT

The Rampart Range Fault trends North-South, the fault forms the eastern margin of the Rampart Range which is also a part of the Colorado Front Range. It has a slip rate of less than 0.2 mm/yr.

 

The fault was severely affected during a slow mountain-building episode called the Laramide Orogeny, which is when the Farallon Plate subducted beneath the North American Lithosphere. The Laramide Orogeny was how the modern-day Rocky Mountains were built, this occurred around 70-40 million years ago.

 

The Rampart Range Fault was reversed during the Laramide Orogeny but shifted to Normal Fault Movement in the Cenozoic. According to the USGS, the fault has 8 meters of down-to-the-west quaternary displacement. 

 

The fault is visible through topographic breaks and vegetation lineaments, along with a well-developed fault-line scrap which is visible along the fault Trace. The fault extends through Precambrian and early Tertiary rocks, The most recent fault movement was during the middle to late Quaternary only 600,000 to 30-50,000 years ago.        

Ute Pass Fault.jpg

RAMPART RANGE

FAULT

UTE PASS

FAULT

REFEreNCES

USGS Quaternary Fault and Fold Database Of The United States Ute Pass Fault (Class A) No. 2327

Widmann, B.L., compiler, 1997, Fault number 2327, Ute Pass fault zone, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 11/15/2019 03:28 PM.

Roadside Geology Of Colorado

Felicie Williams & Halka Chronic

Third Edition

Page 42 - 44 (Garden Of The Gods)

Mountain Press Publishing Company (2014)

Mountains Old And New

National Park Service

Pecos National Historic Park

Garden Of The Gods and Basal Phanerozoic nonconformity in and near Colorado Springs, Colorado

Geological Society Of America Centennial Field Guide - Rocky Mountain Section, 1987

Jeffrey B. Noblett, Andrew S. Cohen, Eric M. Leonard, Bruce M. Loeffler, and Debra A. Gevirtzman

Colorado College, Colorado Springs 80903

USGS Quaternary Fault and Fold Database Of The United States Rampart Range Fault (Class A) No. 2328

Widmann, B.L., compiler, 1997, Fault number 2328, Rampart Range fault, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 11/15/2019 03:32 PM.

Splay Fault

Oxford Reference 

A dictionary of earth sciences (3 ed.)

Oxford University Press - Edited by Michael Allaby

Published in 2008

Geologic Unit: Fountain 

USGS & AASG (Association Of American State Geologists) 

National Geologic Map Database - Geolex

https://ngmdb.usgs.gov/Geolex/UnitRefs/FountainRefs_8179.html

Geologic Formations and Structure of Colorado Springs Area, Colorado

Colorado Geological Survey

L. Throwbridge Grose: Colorado Springs, Colorado

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