Alpine Sports and Geologic Processes
Jeffrey Frederick, CPG-10989
Alpine sports do not necessarily require a very deep under- standing of geology or geologic processes. Mountains, Rock, and Ice can simply be climbed “because it is there,” in the famous words of Sir Edmund Hilary. Mountains can be skied and trails ridden without a single passing thought as to what lies beneath your feet, how it came to be, or what it will look like in 10,000 years. In my younger years, I became obsessed with rock climbing while studying for my undergraduate degree in central New York, and it was a passion of mine for many years. I found a tremendous outlet for rock climbing, and various other alpine sports, while I lived and worked as a geologist in Oregon.
During my time there, I studied and certified as a techni- cal mountain rescue operator on the evenings and weekends. I ultimately participated in many rescues, and even more “recoveries,” in the Cascade Range and beyond. We trained on towering desert basalt columns, welded tuff cliffs in central Oregon, and the basaltic andesites and diorites typical of the high Cascade Range.
The Cascade Range is the product of rather typical active subduction, with an orogenic uplift belt punctuated by strato- volcanoes, calderas, and intrusive and extrusive igneous rocks of primarily intermediate composition (poor in quartz and potassium feldspar). Mt. St. Helen’s epic eruption on May 18, 1980 captivated the nation, showing the destructive and unpredictable nature of the region. But the geologic record of the region shows us that what we have seen in recent history is nothing compared to what this pressure cooker is capable of. For example, the Columbia Plateau located in northern Oregon, southern Washington, and western Idaho covers approximately 190,000 mi2 with basalt. For a little perspec- tive, that’s more area than all of California (158,000 mi2), and a bit less than Texas (266,000 mi2). Did I mention nearly 40,000 mi3 of basalt, most of which was extruded during a 1.5 my window between 17 and 15.5 mya? That’s enough basalt to cover all of New York, one mile deep!
Or slightly east of the High Cascades lies Newberry Crater, a massive shield volcano approximately 20 mi in diameter that has erupted felsic, intermediate, and mafic lavas throughout its history. Its central crater collapsed approximately 500,000 years ago, yielding the beautiful Newberry Caldera with deep alpine lakes and obsidian domes. While dormant, this monster draws tourists, hikers, and bikers , although it remains a potentially active volcano.
Figure 2: Mineral and Chemical composition of igneous rocks, including the diorite and andesite mentioned in this paper. Source: Earth Science
Australia.http://
earthsci.org/mineral/mineral.html. Accessed Jan 17, 2017.
Figure 1: Subduction of Juan de Fuca plate and location of Cascade volcanoes. Source: Topinka, Lyn, USGS/CVO General Interest publication, 1999. Accessed Jan 17, 2017.
While these high mountains are strikingly beautiful, they are also known to the climbing community for their poor rock quality. Loose, fractured, and heavily weathered andesitic rock often provides extreme objective danger, which is another term for “rockfall,” Climbers like to divide the dangers of their chosen obsession into neat buckets: subjective dangers include all of the things I can control; objective dangers are equiva- lent to the finger of God. In terms of risk management then, choosing your weather window not only entails picking some
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
