Final blog

     Castlewood Canyon was created by a long history of volcanic eruptions, and a stream that once carried a large bedload from the weathering Rocky Mountains. The canyon has seen many different climate changes, from wet tropical conditions into warming and cooling phases including the Ice Age that the Earth is still a part of today.

     1000 years from now, Castlewood Canyon will not look different.  Frost weathering that cracks and breaks off large pieces of conglomerate will create more talus and more obstacles for Cherry Creek. The creek bed will have widened and in areas on either side of the canyon, it will be meandering due to point bars, where the water flow deposits sediment, and cut banks, where the water runs deepest and creates a new path.  If snowmelt in the Rockies is low, the perennial stream will seem more like an intermittent stream as it will flood during summer storms and flow very little otherwise.

(photo belongs to me)

     In 10,000 years, the climate will have warmed a little more.Vegetation around the canyon will be limited to plants that can handle an extremely arid environment. I believe the plains of Colorado are experiencing desertification that will dry up the landscape, push out some native species and similarly invite other, more tolerable species.

     When precipitation does occur, it will have extreme effects on slopes above the creek bed. Translational sliding will send whole sections of the slope into the creek bed as the soil becomes separated and breaks. Some areas will see rotational slumps where water (snow or rain) is too heavy for the land. The V shaped valley will be flattening and creating pediment.



    The overland flow will deposit the canyon's sediment on the plains. The material may increase the sediment load and possibly become a braided stream.

     1,000,000 years from now, volcanic eruptions, extreme heating, and extreme cooling will have occurred. If there is another large volcanic eruption near by, it will disrupt the ecology and physical structure of the canyon, rebuilding it with newer rock material. If the deposited material carried downstream or colluvium built up from the down weathering slopes becomes thick and unable to transport, it will block the flow of water back through the canyon and into the plain that lies to the south.

(courtesy http://www.uwgb.edu/dutchs/geolcolbk/aridevolution.htm)

     The Rocky Mountains will have eroded much more through mass wasting that will deposit downstream much like it has in the past. The canyon, though flattened, will be dotted with boulders much like it is now.

(photo belongs to me)

     Undercutting will be evident as groundwater seeps out of the canyon walls and the salt content erodes the bottoms of rock structures.

     Overall, I predict a warming trend for Castlewood Canyon. It will begin to lose vegetation and continue to erode at a faster rate than it will weather. It may move into another Ice Age and experience glacial weathering but more often it will be a dry, arid climate.






Sources:
http://www.dmns.org/main/minisites/ancientdenvers/formations.html
(courtesy http://www.uwgb.edu/dutchs/geolcolbk/aridevolution.htm)

Castlewood Canyon lies in an area that is classified as a BSk climate, meaning it is a cold sem-arid climate. It has characteristics of a highland continental climate. Being so isolated from any major bodies of water (continentality), and lying on the leeward side of the Rocky Mountains, there is low precipitation. The diurnal temperature range is high because of the lack of latent heat. This change may have been much lower before Castlewood's dam broke.
The potential of evapotranspiration is higher than that of actual precipitation, making the air dry.

Snowfall in the winter months creates a higher surface albedo (or reflectivity) which makes it harder to store heat from the sun (latent heat). The El Nino Southern Oscillation tends to tamper with snowfall in the area, as researched by Bob Henson. Henson highlights the pattern of a greater number of large snowfalls in years of El Nino. This shows the number of large snowfalls out of the total number per year.

Another reason the region experiences occasional heavy snowfall is due to the convergence of cP (continental polar) air and mT (maritime tropical) air. The mixture of cold dry air and moist warm air  produces heavy snowfall.

High winds from air masses moving west (the westerlies) filter in and out of the canyon. These are not as intense as the chinook winds that blow through the region. The air goes through rapid heating as it drops from the mountains and over the plains.  Early mornings, I personally have experienced Valley Fog in the canyon, caused by cool air traveling over the moist ground near the creek bed.

Hot summers bring thunderstorms to the area, including mesoscale convectional complexes that develop over the mountains and move onto the plains mid-day. The canyon is subject to flash floods and hail during these times.

dam image: http://www.flickr.com/photos/douglascountyhistory/4768653182/
Bob Henson: https://www2.ucar.edu/atmosnews/opinion/974/tricky-relationship-el-ni-o-and-colorado-snow

Castlewood Canyon is filled with erosional landforms. The most outstanding physical feature in Castlewood Canyon comes from the conglomerate caprock. These rocks, due to joints and fractures caused by frost wedging, create rock fall all around the canyon. It is littered with sedimentary boulders to tiny bits of rhyolite. The rock fall creates colluvium at the base of some of the slopes and talus in every corner of the canyon. The talus is made of a large number of boulders that designate trails and the overland flow of the creek.

Some of these beautiful  boulders have alveoli and many show further signs of frost weathering.


The water cuts a narrow path through the canyon that weaves through the toppled rock and debris. There are sand pits above the water table where it is obvious water once flowed with much more velocity for a long period of time.

In my experience, there are times when the water is ankle deep and if you walk up stream from the main waterfall, you can feel a distinctly colder flow of water that comes from deep underneath a specific rock. Groundwater is colder than surface water which leads me to believe the water table here is being fed by groundwater which would make it an effluent stream. There is also evidence of historically frequent flash floods.  In this arid climate, the permeability of the rock and soil in the canyon is low. There are rills in the slopes where water from the top of the canyon joins the creek. Debris can still be found amongst the boulders.

Another significant characteristic of the canyon is in the steep slopes above the water. They are layered in many strata and can be classified as Mollisol as a result of calcification. They show healthy vegetation in the O -Horizon and a darker humus A-Horizon. Most of these slopes seem to have been revealed by translational slides that have created colluvium at the bottom. Most of this colluvium has been taken by the water and deposited as alluvium. Other slopes around the canyon are rotational slumps and appear rounded.

 

--All photos taken by me! The blogger site will not allow me to change the size of my pictures, sorry for the size!

Castlewood Canyon's geologic history, though spanning millions and millions of years, is rather busy. Sitting on the edge of the Palmer Divide, this felsic, sedimentary paradise contains 3 significant geologic formations from different time periods.

(Photo provided by http://fieldguides.gsapubs.org/content/3/59.full)

The first, and oldest type of rock found in Castlewood Canyon forms a wide, slanted edge that falls into the Cherry Creek bed. This is the Dawson Arkose formation made from conglomerate, sandstone, and shale (USGS ). This rock also contains biologic elements including fossils and petrified wood left over from a tropical rainforest that once thrived on the land (CO State Parks).

This rock was covered 36.7 million years ago when a super volcano near what is now Salida, Colorado, erupted (CO State Parks). A large layer of extrusive rhyolite (known also as Wall Mountain Tuff in this area) was formed and hot volcanic ash and magma lithified its surroundings.

The upper portion and caprock of Castlewood Canyon's walls is formed by enormous, distinctive conglomerate boulders. These conglomerate rocks are described as "the coarsest of all the Cenozoic conglomerates and gravels in the Colorado Great Plains sequence," and dot the canyon because they were once swept by water from the Rocky Mountains into the canyon (Field Guides). They are the first noticable feature of the canyon's geologic profile and the most accessible; many have fallen from the top of the weathering canyon walls and into the creek bed below. The water that has been flowing through what is now Cherry Creek has cut through the resistant, cement-like conglomerate, rhyolite, and into the softer Dawson Arkose.

(map provided by http://fieldguides.gsapubs.org/content/3/59/F4.expansion.html).


US Geological Survey: http://tin.er.usgs.gov/geology/state/sgmc-unit.php?unit=COTdu%3B0

Colorado State Parks: http://www.parks.state.co.us/Parks/CastlewoodCanyon/Publications/Pages/CastlewoodPublications.aspx

Field Guides: http://fieldguides.gsapubs.org/content/3/59.full

I love this place!

Welcome!

My name is Jill Rosenberger and I am currently trying to finish up my degree in Geography at the University of Colorado Denver.

When we were asked to focus on a location and pick apart its physical attributes, I immediately thought of a place that has been to dear to me for many years. Castlewood Canyon is a state park south on highway 83 (better known as Parker Road). Castlewood Canyon lies just a few minutes from where I grew up and where I graduated from Ponderosa High School. It was the place to be for high school  students who had found their way off campus for the day. We recklessly climbed the boulders, sat atop the historic broken dam, and peered into small caves. Castlewood Canyon was a haven for us because it was an unbelievable scar in the land and it bore natural treasures that I still find when I hike there today.

I still frequent Castlewood ,as we fondly call it, as much as I have time for. I am a little more cautious about the obvious dangers it presents (rattlesnakes, long falls, jagged rocks) but I am also a little more knowledgeable about the history of the canyon. I recently did a research paper about the environmental history of this ancient place and it provided me with loads of interesting information regarding its human history. From family groups in a wooded landscape to pioneers of the west, what was once Wildcat Canyon has played a colorful role in the lives of humans who have lived in this region. The research gave me names and dates for the formations that created Castlewood Canyon, but I am excited to learn more about what they mean, which volcanoes they were spewed from, and how its physical features ultimately define its natural beauty.