The Castlegate Sandstone and The Miners

On my recent field trip to Utah with the MYRES group we also visited an outcrop of the Castlegate Sandstone (Book Cliffs – click here for more information). This particular section shows fluvial sandstones that are intercalated with abundant coal intervals. Hajek and Heller (2012) described this units as follows : “The Castlegate Sandstone was deposited in a foreland basin by rivers that flowed eastward off of the adjacent Sevier Orogenic Belt into the Cretaceous Interior Seaway (Fouch et al., 1983). The base of the section is considered to be the Castlegate sequence boundary (CSB), across which fluvial Castlegate Sandstone deposits are juxtaposed atop fluvio-deltaic sandstones of the Blackhawk Formation (Campanian; Fouch et al. 1983). In its type section just north of Helper, Utah, the Castlegate Sandstone is divided into three informal units (Fouch et al. 1983): the lower, cliff-forming sandstone-dominated interval, widely interpreted as resulting from braided-river deposition (e.g., Chan and Pfaff 1991; Miall 1994; Adams and Bhattacharya 2005; McLaurin and Steel 2007); the middle mudstone-dominated interval with isolated sandstone channel-belt deposits, interpreted as sinuous single-thread river deposits (e.g., Chan and Pfaff 1991); and the upper “Bluecastle Tongue” of the Castlegate Sandstone, a sandstone-dominated, cliff-forming interval. In general the Castlegate Sandstone in its type area is wholly fluvial in origin; however, evidence of tidal and brackish water influence has been reported in the middle Castlegate interval in the type locality (McLaurin and Steel 2000).”

MYRESV participants attacking the outcrop! Picture by Lorena Moscardelli

Castlegate Sandstone - Fluvial sandstones intercalated with abundant coal intervals. Picture by Lorena Moscardelli

Hajek and Heller (2012) used LIDAR images of fully preserved bar clinoforms from the Castlegate Sandstone to measure clinoform heights and used these measurements as a proxy for paleoflow depth.

This particular outcrop is located near a power plant and several coal mines that have been operating in this region for decades. Obviously, the Castlegate Sandstone with its abundant coal intervals is an important component of the energy and economic equation in this region. However, we should not forget that the coal business is not only dirty (from an environmental perspective) but also dangerous (in a more tangible way). On March 8, 1924 an explosion occurred in the Castle Gate No.2 Mine that instantly killed 171 miners and one emergency worker. The majority of the miners were immigrants who left 241 children behind and 25 expectant mothers. Unfortunately, this was not the last tragedy in this region and on July 31, 2000 an explosion on the Willow Creek Mine took the lives of 2 miners sending 8 more to the hospital. After this last explosion, the Willow Creek Mine was closed for good. Energy has a price that sometimes is just too high.

Memorial Willow Creek Mine Explosion - July 31, 2000

Castle Gate Mine Disaster - March 8, 1924 

References:

Hajek and Heller (2012) Flow-depth scaling in alluvial architecture and nonmarine sequence stratigraphy: Example from the Castlegate Sandstone, Central Utah, USA. Journal of Sedimentary Research, v. 82, 121-130

The Thistle Landslide

I was recently invited to attend the MYRES 2012 meeting. MYRES stands for “Meeting of Young Researchers in Earth Sciences” This is a “community building effort dedicated to young scientists in Earth Sciences. The effort is centered on a biannual meeting during which various interdisciplinary approaches are presented to try to solve a common geological or geophysical problem.” This year’s theme was “The Sedimentary Record of Landscape Dynamics” and it was organized by a group of very smart/cool/young scientists working for a variety of academic, governmental and private institutions. The meeting was hosted by the University of Utah in Salt Lake City where we spent several days listening to presentations and brainstorming about the future of our respective disciplines. We also spent a lot of time talking about community efforts and how to integrate sub-disciplines to try to solve the ‘bigger questions’ of the source-to-sink conundrum (I’ll be posting more about this later). At the end of the week, we embarked into a wonderful field trip through Utah and my summarizing comment is “there are a lot of exposed rocks in that part of the world.” We were looking at the stratigraphy as well as to modern surface processes and since I have a special passion for all things mass-wasted, I’ll start by sharing with you information about the “Thistle Landslide”.

Thistle landslide, August 2012 (Photo by Lorena Moscardelli)

According to the Utah Geological Survey, the Thistle Landslide was the most costly landslide in U.S. history (at least before 2005): “Record-breaking precipitation in the fall of 1982, followed by a deep winter snow pack, then warm spring temperatures and rapid snowmelt in 1983 set the stage for the Thistle landslide. Once triggered, the slide reached a maximum speed of 3.5 feet per hour and dammed Spanish Fork River within a few days.” You can read more about this landslide here. It’s a really fascinating story since it allows us to appreciate the real impact of geological process in a very human time scale! The other thing that I think is fascinating is the fact that in the equivalent time of “less than a second” (geologic time scale!) this particular process generated a deep scar on the landscape and a deposit that has a good chance of preservation (maybe? partial preservation?). It makes you wonder, how much of the geologic record is dominated by short-termed lived catastrophic processes? I am a catastrophist by nature but I am just saying… 

  

If you want to see more of the geology of Utah download this plug-in for GoogleEarth!

Update:

After I posted this entry, I saw a video of a mudflow that took place last week in Austria - click here to watch video. You will see that the nature of this event is more catastrophic than the Thistle Landslide since the last one only traveled at maximum speeds of 3.5 feet per hour. The original rheology of the failing material has a great deal to do with these differences. Really amazing!