United States – Page 7

cross-cutting relations (pan)

October 7, 2014/in California, Death Valley National Park, Mojave Desert, United States/by Marli Miller

A canyon wall on west side of Panamint Valley in SE California –part of Death Valley National Park. (Image ID# pan-rainbowunconf)

Sawtooth Peak

October 4, 2014/in California, Sierra Nevada, United States/by Marli Miller

Sawtooth Peak (right) capped by Columbia River Basalt. Beneath it is granite of the Wallow Batholith –and off to the left, are the bedded rocks of the Martin Bridge Limestone. (Image ID# 140713-43s)

Wallowa Mountains, Oregon

October 4, 2014/in fault, fault zone, Joseph, Oregon, Wallowa Mountains Oregon, United States, Whitman National Forest/by Marli Miller

fault-controlled

Sawtooth Peak, California

October 4, 2014/in California, non-geology, Sierra Nevada, United States/by Marli Miller

Sawtooth Peak (right) capped by Columbia River Basalt. Beneath it is granite of the Wallowa Batholith –and off to the left, are the bedded rocks of the Martin Bridge Limestone. (Image ID# 140713-43e)

Mudcracks and Ripple Marks

October 1, 2014/in Idaho, Montana, United States/by Marli Miller

Mudcracks (left) and ripple marks (right) in rock of the Belt Supergroup. The mudcrack is about 20cm across; the ripple marks are roughly 1m across. (Image ID# belt-sedsrs-pic)

Cloudy Peaks

October 1, 2014/in Glacier National Park, Miscellaneous, Montana, United States/by Marli Miller

Bright mountain peaks guard a quiet river. (Image ID# 140720-6)

Proterozoic stromatolite (vertical)

October 1, 2014/in Fossils, Glacier National Park, Instagram Pics, Montana, United States/by Marli Miller

limestone, laminations, algal mat, Precambrian, stromatalites

Granite intruding Gneiss

September 27, 2014/in Colorado, Rocky Mountain National Park, United States/by Marli Miller

1.4 billion year old granite intruding 1.7 billion year old gneiss. (Image ID# ig-23)

Glacial Cirques, Colorado

September 27, 2014/in Colorado, Glacially carved landscape, Rocky Mountain National Park Colorado, Glaciation, Rocky Mountain National Park, United States/by Marli Miller

erosion, abrasion

April 6, 2012/in San Andreas Fault, Tomales Bay California, San Andreas Fault/by Marli Miller

Marine Transgression diagram

April 4, 2012/in Limestone, Marine Transgression, sandstone, shale Arizona, Miscellaneous, Montana, non-geology, United States, Wyoming/by Marli Miller

If you look at Time 1, you can see a coastline in cross-section, with sand being deposited closest to shore, mud a little farther out, and eventually carbonate material even farther out. As sea levels rise in Time 2, the sites of deposition for these materials migrates landward, putting mud deposition on top the earlier sand deposition and so on. In time 3, the sequence moves even farther landward, resulting in carbonate over mud over sand. If these materials become preserved and turned into rock, they form the sequence sandstone overlain by shale overlain by limestone – just what we see on top the Great Unconformity. (Image ID# transgression)

tetons-panlr

April 2, 2012/in metamorphic and igneous rock Teton Range Grand Teton National Park, non-geology, United States, Wyoming/by Marli Miller

Great Unconformity in Wyoming

April 2, 2012/in Precambrian, Teton Range, unconformity, Wyoming Grand Teton National Park, United States, Wyoming/by Marli Miller

The yellow arrow points to the contact between the Cambrian Sandstone and underlying Precambrian metamorphic rock. This area is called the Great Unconformity of Powell, named after it’s first observer John Wesley Powell in 1869. (Image ID# sru-14e)