The Earth Story

The Top Step Last week, we covered the geology of the Grand Staircase in Utah – a large sequence of nearly undisturbed sedimentary rocks that starts at the Great Unconformity in the Grand Canyon and marches across Arizona and Utah, eventually reaching Paleocene-Eocene aged rocks that are as young as 40 million years old. This sequence creates a “Staircase” pattern as the more easily eroded units create large flat areas and they are then separated from more resistant units that create steps upwards. This image captured out a plane window captures the uppermost step in the Grand Staircase and a particularly famous National Park. 

Goblin Valley

We’ve done a number of posts about hoodoos (for a complete list, see below), but only because they really are THAT cool. Here’s one more hoodoo picture to add to our list: the hoodoos of Goblin Valley State Park, Utah.

Hoodoos are the delicate masterpiece of differential weathering, wind, and water. The hoodoos here (nicknamed “goblins”) are composed of the Entrada Sandstone, a Jurassic-aged sandstone made up of shoreline deposits. Do they look familiar by any chance? These goblins made their cinematic debut in 1999 as an otherworldly backdrop for the movie Galaxy Quest.

Although it may look tempting, do NOT knock any of these goblins over if you happen to visit. After all, they are about 25 million years in the making. Toppling them could earn you thousands of dollars in fines and even imprisonment. -CM

For more about hoodoos: http://on.fb.me/1F5weP2 http://on.fb.me/1GKCLAN http://on.fb.me/1wBhypC http://bit.ly/1BatWIw http://on.fb.me/1b6lCEV http://on.fb.me/1NQxVE4

Photos courtesy of me and MrA

Wind, ice and sand

Wandering along the beaches of an icy Lake Michigan, the photographer spotted these foot high baby yardangs (aka hoodoos) on the normally sandy beach. Dozens of these towers were rising up over what had been a flat expanse of sand, and the life cycle of this phenomenon reveals in a few days or weeks erosional processes that take many millennia or more in rocks. The beach was frozen in the winter cold, solidifying. The ice (which is also a mineral) cemented the grains into a temporary, temperature mediated sandstone, in much the same way as calcite or silica from the waters that percolate the depths of the Earth do to sediments during their transformation into rock (a complex set of processes known as diagenesis). The howling winter winds then eroded the beach in the same way that they would a sandstone, but much faster than usual since ice is a lot softer than the usual mineral cements found in sedimentary rocks.

A couple of days later (these were taken on Valentine's day), he returned to check on them, but a rise in temperature had dissolved them all, melting their icy cement.

Geological processes are fractalic as I keep on emphasising, recurring across scales from the tiny to the huge (see http://on.fb.me/1L72vp3). Yardangs many tens of metres tall exist, as do these beautiful tiddlers. This process reveals another fractalic dimension, that of motion through time. The same processes took place over a couple of days, rather than the usual millions of years.

Loz

Image credit: Joshua Novicki. http://joshuanowicki.smugmug.com/ http://earthsky.org/todays-image/wind-sculpted-this-frozen-sand-in-michigan http://www.thisiscolossal.com/2015/02/ice-sand-scultpures-lake-michigan/

Hoodoo Birth

This photo comes from a location in the state of Utah known as Sidestep canyon. It’s off the beaten path from the major national parks, but one treat of the Western US is that the same features that define national parks like Bryce Canyon can be found in a number of spots. In this location you can see one of Bryce’s most famous features, Hoodoos, being born.

Hoodoos are spires of rock that stand up in desert regions. They form when small amounts of water get into cracks in rocks and force them apart through a combination of erosion and frost wedging – expansion and contraction of water as it freezes adds a force that breaks the hoodoos apart.

The layering in hoodoos reflects the strength of the sedimentary rocks. More easily eroded layers become thinner, while stronger layers hold together and often form caps. Once water breaks through a cap, it can begin separating the rocks into these rough features.

-JBB

Image credit: John Fowler https://www.flickr.com/photos/snowpeak/15686755802/

Read more about hoodoos: http://www.nps.gov/brca/naturescience/hoodoos.htm Sidestep Canyon: http://fridrich.binghamton.edu/Sidestep%20canyon/index.html http://www.thewave.info/UpperWhiteRocksCode/Map.html

The Most Photographed Place in Utah

About 15 kilometers west of Utah’s Bryce Canyon National Park is Red Canyon, part of the Dixie National Forest in the U.S. Red Canyon is sometimes called the “most photographed place in Utah”. The canyon is defined by red-orange sandstone and filled with green conifer trees making the area very photogenic.

During the Paleozoic Era (542 million to 251 million years ago), the area was periodically a tropical inland sea, depositing limestone, sandstone, siltstone, and shale; then the sea would retreat and allow stream deposits and sand dunes to build up. The cycle continued for about 300 million years until geologic uplift pushed up the elevation enough that shallow seas could no longer form. Rivers, streams, and lakes begin to erode the deposits to create unique landforms, including hoodoos and Bryce Canyon, as previously coveredhttp://on.fb.me/1w4q7an.

Red Canyon is part of the Paunsaugunt Plateau, which formed 10 to 20 million years ago from a geologic uplift of the larger Colorado Plateau. The sandstone rocks of the canyon have high concentrations of iron, which gives them their red color. Like Bryce Canyon, Red Canyon also has hoodoos and other similar rock features which add to the photographic appeal of the area.

Photo credit: Xanthi Merlo http://rectrix.net/photography-portfolio/

Read More: http://www.fs.usda.gov/recarea/dixie/specialplaces/recarea/?recid=24942&actid=120 http://www.brycecanyoncountry.com/paunsaugunt-plateau/ http://geomaps.wr.usgs.gov/parks/province/coloplat.html