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Ascent of Castle Rock on 2017-07-16

Climber: William Musser

Others in Party:Karen Musser
Date:Sunday, July 16, 2017
Ascent Type:Successful Summit Attained
Peak:Castle Rock
    Location:USA-Colorado
    Elevation:6585 ft / 2007 m

Ascent Trip Report

Turned out to be a surprisingly fun hike. First of all (1)it is a crazy landmark to see as you drive into town. Second, (2) it is easy parking and well maintained trails class 1; (3) the views are good on the way up and at the top; (4) there is a nice pure class 3 scramble at the end which is very rewarding since you look at the rock from many directions and wonder where a natural safe seem would present itself and it does; (5) for those that like exposed scrambling there is plenty of that too but the standard route is completely class 3 where you can ascend down facing down and never with exposure but it is true class 3 climbing with hand holds and long reaches. Fun, even if only about 50 feet to the top; (6) wildlife was crazy cool - I saw several fence lizards, a cottontail rabbit; several cliff dwelling birds, and had some very odd experiences with insects to be discussed later; (7) the geology is fascinating! I have never hiked on such interesting conglomerate material made up of everything from sand and pea sized rounded material to huge boulders entrapped in the rock. More on this later...

Geology - the entrapment of the many shapes, sizes, and materials in the conglomerate rock indicates that some very powerful force like a rapid pyroclastic flow obliterated and scraped up material (mostly rounded fluvial looking rock) and compacted it in ash and layered it into thick conglomerate sandstone rock that is now exposed. I sensed this was a catastrophic volcanic event based on what I was seeing and near the top I spotted vesicular rhyolite (another indicator of volcanism). The thickness of this indicates it was a massive event! I also found beautiful specimens of microcrystalline rhyolite broken open with smooth glassy texture but surrounded with a quarter inch thick layer of welded conglomerate sedimentary material on the outside. You could envision the molten magma rolling in the material like a doe ball and sticking and welding the sedimentary rocks. Later, I will research the internet to verify my interpretation of this fascinating landscape.

Insects - Two weird events. First, as soon as Karen and I and another random couple summited and went to take photos at the peak, we became swarmed in some small insect cloud. At first I thought it was gnats, but soon I realized we were invaded by thousands of swarming winged ants! They got tangled in all of our hair and started crawling down our shirts! We rushed away from their nest and got them off of us and tried to go back and once again I was swarmed right on top of the actual peak!.....we all retreated and brushed them off for a second time and then near the scramble area seam and we saw a shrub and it was moving so we went over and a third swarm engulfed us. That was enough! We scrambled back down and got them all out of our hair. I have never had that many insects on me at one time in my life. They do not bite. They simply cover you and crawl all over you.

If that was not odd enough, near the bottom of the scramble I saw some class 3+ to class 4 scrambles over to some very exciting ledges and caves. On my way up to investigate them my wife cried out do not go in there and she warned me that she saw a lot of wasp activity ahead. Sure enough where I was about to put my hand in one of the natural hand holes in the climbing rock was now occupied by a nest of hornet like creatures (probably a dozen or so). If I had proceeded I might have had a hand stung horribly by a nest as I was climbing!

A beautiful and interesting hike but enough insects for me for the day so we headed down. I will come back. A short but fun rewarding hike.


UPDATE:......I found this on the internet; appears my interpretation was pretty spot on

from "A Geological Tour of Denver, Golden, and Colorado's Front Range
Wall Mountain Tuff"

A moving cloud of gas and ash...

Mount Princeton, in the Sawatch Range, is about 85 miles west of Colorado Springs. A body of magma which formed in the region of Mount Princeton 36.7 million years ago suddenly found a weak area in the surface rocks and explosively broke through. A mixture of molten magma, pumice, ash, glass, and rock exploded into the atmosphere and formed a cloud which began moving or "flowing" downslope. Pyroclastic flows, as such moving clouds are known, can be very hot, with temperatures reaching between 500 and 1,000 degrees C (932 - 1,800 degrees F). The cloud, perhaps moving at 50 to 100 miles an hour, probably reached what is now the city of Castle Rock, some 90 miles to the northeast, within two hours or less.

The ash which settles out of a pyroclastic cloud is known as tuff. Sometimes the pyroclastic globules, which are very sticky, pick up ash and the combination precipitates out of the cloud as welded tuff. In other instances they cool quickly and fall in the form of powder or volcanic ash, a form known as soft tuff. Welded tuff can also take the form of rhyolite, a fine-grained, compact, form considered the volcanic equivalent of granite. It is usually light brown to gray in color.

The pyroclastic cloud which reached the Castle Rock area was still very hot. As a result, much of what came out of the cloud was a form of welded tuff. It has been called the Wall Mountain Tuff or, alternatively, Castle Rock Rhyolite. At the time, the region was probably a flat plain. The amount of material emerging from the Mount Princeton explosion was substantial, since the deposited layer was, in places, at least twenty feet thick.

The "Castle Rock" formation, for which the town is named, has the appearance of an island standing high above the surrounding plain, bearing the brunt of the volcanic eruption. The reverse is true. The present formation was one of the lowest points around. In addition, it is not even part of the original deposit of volcanic material, which somehow avoided erosion, but instead, a form of conglomerate, known as Castle Rock Conglomerate. Over millions of years, water and streams began to cut paths through the rock, creating canyons. The area seems to have been particularly hard hit by floods around 34 million years ago. The rhyolite broke apart and the chunks fell into a streambed as they eroded from the canyon walls, to be reformed and cemented together as conglomerate. Below the Castle Rock Conglomerate is Dawson Arkose, a feldspar-rich sandstone. The ash and tuff from the Mount Princeton eruption was falling on what had been an accumulation of sand, an alluvial fan created by the continued erosion of the then existing Rocky Mountains.
Summary Total Data
    Total Elevation Gain:415 ft / 126 m
    Total Elevation Loss:30 ft / 9 m
    Round-Trip Distance:1.5 mi / 2.4 km
    Grade/Class:1 and 3 finish
    Quality:7 (on a subjective 1-10 scale)
    Route Conditions:
Maintained Trail, Scramble
Ascent Statistics
    Gain on way in:385 ft / 117 m
    Distance:0.7 mi / 1.1 km
    Route:standard loop (right)
    Start Trailhead:Parking lot city park  6200 ft / 1889 m
Descent Statistics
    Loss on way out:30 ft / 9 m
    Gain on way out:30 ft / 9 m
    Distance:0.8 mi / 1.3 km
    Route:extra scamnling and down same way



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