Mesa Verde National Park, whose name can be a bit deceiving because the area is a cuesta, not a mesa, was “established in the year 1906 by Theodore Roosevelt in order to preserve the works of man” (“History & Culture”). “The only difference between a cuesta and a mesa is that a cuesta gently dips in one direction” (Service, National Park). “Mesa Verde was once home to the ancestral Puebloans living there for more than 700 years. They flourished here, building elaborate stone communities in the sheltered alcoves of the canyon walls. The park contains over 4,000 known archeological sites including cliff dwellings and the mesa top sites of pit houses, pueblos, masonry towers, and farming structures” (“Places”). The geology of Mesa Verde is what …show more content…
“The geological formations of Mesa Verde National Park were mainly deposited about 100 to 75 million years ago, when the Western Interior Seaway covered all the way to the middle of the continent. At this this time, the sea deposited many different types of sediment. When the sea first reached the Mesa Verde area, it deposited layers of sand” (“Geology of Mesa Verde”). Afterwards, “when the sea advanced farther westward the sandy deposits changed to deeper water shale deposits; called the Mancos Shale. It consisted of fine particles and organic fossil material. The shale forms the low hills you see at the base of the mesa in the Montezuma Valley” (“Geology of Mesa Verde”). “The next formation, Point Lookout Sandstone, deposited as beach sand as the sea retreated again, is mainly composed of sandstone with some shale lenses dispersed throughout. Small alcoves form in this sandstone layer, but these were not often used by the Ancestral Puebloans” (“Geology of Mesa Verde”). As you can start to see, Mesa Verde is already developing many of the key features we see today and that the …show more content…
“Concretions, which are compact masses of mineral that form within a pre-existing rock. These nodules are often spherical, elongate, and are harder than the rocks that contain them. They develop around an irregularity within the rock that serves as a nucleus, often a piece of shell, a pebble, or just a harder spot in the rock. As water runs through the rock, it deposits minerals at these irregular spots. Most of the concretions are in the Cliff House Sandstone” (Service, National Park). “Other features are on many of the cliff faces, called desert varnish. Desert varnish forms when manganese, a mineral found either within the rock or in windblown dust, is fixed to the cliff face by bacteria. The bacterial action occurs on the portions of rock wet from runoff water, causing a streaking effect” (Service, National Park). Another distinctive feature called turtle back weathering, develops in the Cliff House Sandstone that is exposed and unprotected on mesa tops. Originally, there was about 1500 feet of rock atop the Cliff House Sandstone. As this overlying rock eroded away, it released a tremendous amount of pressure on the sandstone. The pressure release caused cracks to form in the rocks. Water then weathered these cracks through freezing and thawing or by dissolving some of the
Yes this feature is the result of erosion and depositional processes however, it is not associated with the current water course. This feature may be the result of a Gilbert type delta that once occupied this area. Gilbert type deltas have three main components; topsets, foresets and bottomsets. Topsets are fluvial sediments (primarily sandur deposits) that were deposited on the subaerial delta surface. Erosive events occurring on the upper forslope can result in downslope channels and chutes. These features are then eroded by either strong currents or by debris flow resulting in these channels and chutes to become filled. Foresets are a combination of sand and gravel facies. The are deposited by gravitational processes on the delta foreslope and the grains tend to become finer and more angular downslope. Bottomsets consist of fine grained silts and clay and are deposited at the foot of the delta front.
1. 225 MY : Weathering and erosion of very old folded rocks on an area
...e morphed it into the quartzite that is seen surrounding the butte (4). Rocks that undergo this process are called metamorphic rock, which is the same as the rock seen years ago by dinosaurs and other extinct creatures. The quartzite rocks were formerly seafloor sediment that was forced upwards, and then surrounded by lava basalt flows. Once erupted through fissures and floods through out most of the area, lava flow eventually created enough basalt to form a thickness of about 1.8 kilometers (1). All of this basalt flow eventually led to the covering of most mountains, leaving the buttes uncovered. The igneous lava flows and loess is reasons that the Palouse consists of such sprawling hills, and rich soil for farming (2). In result of the lava flows, the Precambrian rock Quartzite was formed. And lastly covered by the glacial loess, which were carried by the wind.
The coastal belt of the Franciscan Complex is composed of the youngest and least deformed units and makes up the western quarter of all Franciscan rocks. The rocks of the coastal belt are composed of arkosic sandstones, andesitic graywackes, and quartzofeldspathic graywackes interbedded with radiolarian chert (turbidite deposits) (Blake and Jones, 1981). These sedimentary rocks suggest a depositional environment of deep-sea fan systems with both oceanic and continental provenance. Parts of the belt show evidence of later metamorphism, principally due to subduction. Low-grade blueschist mineral facies are indicated by the presence of minerals such as laumonite and prehnite-pumpellyite (Blake and Jones, 1981). All rock units show evidence of thrust (imbricate) faulting due to the compressional forces of subduction. Ages of the coastal belt run from as little as 40 Ma (Eocene) to as old as 100 Ma (middle Cretaceous).
Tarbuck E., Lutgens F., Tasa D., 2014, An Introduction to Physical Geology, 5th Ed, Pearson Education, Upper Saddle River, New Jersey.
This sedimentary rock has hardened over the many years with sand shells, small pebbles, grains of sand and rocks of various sizes. In comparison to our 4.5 billion year old Earth, these sand shells might as well be brand new, when in reality they could be up to 1,000 years old. If the sandstone were to be replaced with calcite it would completely change the subclass of rock, it would then be chemical & organic limestone. The variation in sand stone is due to different rates of deposition and change in patterns of the sediment movement (Mc Knight, p. 384). These tightly compacted varying stones and shells will be weathered away by wind and waves over time and could eventually be reduced to a rock the size of your hand.
Imagine a scenic, wild landscape with animals that roam freely, cascading waterfalls, and mountains that seem to scrape the pale blue sky. This is what one thinks when first hearing the name Yosemite National Park. Unfortunately, the reality is completely opposite. Yosemite is now under a federally regulated Class 1 area under the Clean Air Act, which is equivalent to the pollution of Los Angeles (“National Parks Service”). It is a sad comparison to the past John Muir, who first documented Yosemite Valley, to today’s reality. The condition of Yosemite National Park should be introduced to the American public in order to protect its historic beauty and significance, eliminate current pollution, and prevent future repercussions.
The Little Missouri River eroding the mountain range is the reason that the park is as it looks today. The park is believed to be <60 million years old. Over 60 million years ago volcanos all over the west were erupting and spitting out amounts of ash. The rivers near the volcanos were gathering. The rivers began to dry out, leveeing the ash behind. The ash was being dried in layers and turned into sandstone, siltstone and mudstone while the ash layers became bentonite clay. This Bentonite clay is dangerous because it gets people stuck, like quick sand it is located throughout the park. It can pull the car tires un...
"Sedimentary Rocks." Backyard Nature with Jim Conrad. N.p., 18 May 2015. Web. 25 Oct. 2015.
Zig-zag, back and forth, down, down, down, Jonathon, Dad, and I went into a mysterious new world. Now that I have gone into this hot, dry canyon surrounded by monstrous hoodoos, I have seen what it is really like to leave the small town of Seymour, and emerge into the greatness of this world. I have now seen several other National Parks on one of the most renowned places on earth for mysterious creations, the Colorado Plateau. Of all the beautiful places on it, even the Grand Canyon, I have found my favorite one. Bryce Canyon National Park. I thought it was amazing, because it was the most diverse to anything I have ever seen before. We hiked down into it and I felt like I was surrounded by skyscrapers. We trekked around a little, but we didn’t
The Arrastre Wash is a region which contains interesting geologic structures, and it is located on the west side of the city of Tucson in the Tucson Mountain Park. This region is predominantly composed by sedimentary rocks from the lower Cretaceous such as sandstone and shale, which can be distinguished by the grain size, and the conglomerates from the Quaternary. The rocks from the lower Cretaceous were deposited on an alluvial environment in which the energy of transport sediments varied. The outcrops were twisted, folded and uplifted
The Don Valley Brickwork consists of many different layers of geological deposits, allowing us to observe and have a better understanding of how the sediments we see today are formed. The most bottom layer in the Brickworks are from the Georgian Bay Formation, and consists of grey- shale bedrocks. Fossils are often found in this layer and it is estimated that this deposit of sediments is around 445 million years old. Above the bedrocks is a thin layer of grey clay sand and gavels left behind by the Illinoian Glacier. This layer is called the York Till and occurred around 135,000 years ago. The next layer consists of a sandy deposit called the Don Formation, which is formed by the Sangamonian Interglacial Stage. Many plant and animal fossils are found in this layer due to warmer climate around 120,000 years ago. Above it lies the Scarborough Formation, which consist of clay and sand. This sediment likely occurred 115 - 106,000 years ago. The next layer above is the Poetry Road Formation, and consist of sand and gravel. This layer is likely formed during the early Wisconsin glacial substage around 106- 75,000 years ago. Higher is the Sunnybrook Drift which was formed 60 – 75,000 years ago. And on the surface, is the Halton Till, which was left behind by the final push of the Wisconsin Glacier.
The geology, its history, and the presence of past civilizations contribute to much of the significance of Mesa Verde National Park. The interconnectedness of these aspects should also be noted. If not for the weathering processes and changes in sea level this formation would not exist. Without it, the ancient people would not have been able to reside within Mesa Verde. This National Park now serves as a tool to help conserve the remains of these past civilizations as well as to help educate today’s society on the significance behind this astonishing geologic
Blakey, R. C. (1996). Geologic history of western us. Informally published manuscript, Northern Arizona Univ, Flagstaff, AZ, Retrieved from http://www.jan.ucc.nau.edu
...11). They were cliff dwellers and built adobe homes, hunted, grew crops, formed villages and learned to make pottery mostly in the Mesa Verde region from around 1050. They are essential to history as they are some of the first developers of the great cliff dwellings as well as the land amongst Colorado, New Mexico, Utah, and Arizona. They left Colorado, thanks mainly to drought and war. However, they have returned numerous times since their disappearance in the 1200’s and their history continues on through their descendants (Abbott, Leonard, Noel, 2013, pp. 12).