This section will discuss the geological history of the area for each lithological formation, as well as identify the main structures and what these were caused by.
The Millstone Grit at its base has an unconformity formed by uplift and folding of a northerly landmass. It has a thick series of quartzitic sandstones formed from weathering of an earlier landscape. There are several movements due to subsidence, which can be seen in the Millstone Grit through the basal grits. Following the Millstone Grit the coal measures were deposited with a gradual change due to increasing sea levels.
The lowest coal measures are classified at the base, by the shallowest water seen by the presence of plant roots. During the lower coal measures, large amounts of vegetation grew to enable the process of coal formation to begin. Plant growth became more prominent at the end of this period, shown by the significant coal seams at the top of the lower coal measures (Archer, 1968).
The middle coal measures were formed in a similar environment, they also contain marine bands such as the Upper Cwmgorse. These were formed as sea level rose and fell in the Carboniferous driven by Gondwana ice cap fluctuations producing marine transgression onto the South Wales Coalfield delta plain (Isbell et al, 2003). The surrounding sediments to the coal seams are generally mudstones with small amounts of sandstones. The depositional setting of the coal measures is an upper coastal deltaic flood plain with a dominant provenance direction from a southerly landmass (Archer, 1968). The middle coal measures have major fluvial channels flowing through them; these measures are constrained by cross fault activity and the presence of subsiding basement highs (Hartley 1993).
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...lor et al (1998). This plant matter is rapidly buried and compacted in anaerobic conditions forming a unique rock with several economic uses (Archer, 1968).
There are many depositional models of the formation of coal. The most relevant one to this area of study is the upper delta plain facies, as illustrated in Figure 2. This facies is characterised by coarsening upwards sequences of mudstone into siltstones then sandstones; these are known as para-sequences. Coal seams can be traced over large areas, which thin to poor quality coals. The formation of coal occurs as raised mires, which are locally eroded by channels known as washouts and are topped by sheet flood deposits (Guion et al, 1995). These channels are highly variable in size and are constantly changing making it hard to model without sufficient data, as the coal seams vary on a meter scale (Thomas, 2002).
Marshak, S. (2009) Essentials of Geology, 3rd ed. New York: W.W. Norton & Company, ch. 11, p. 298-320.
The shelf-edge includes carbonate-to-clastic facies transition and tectonic uplift and erosion of the carbonates followed by deposition of the clastics. The Saint Peter Sandstone is a well-sorted, almost pure quartz arenite deposited during a major mid-Ordovician low stand. Clastics spread across an exposed carbonate platform by transportation. This is shown by the well-rounded, frosted texture of the quartz grains.
17. The diagram to the right illustrates what type of geologic event? Explain. (S6E5e, f)
Lithologically the Kimmeridge Clay Formation can be subdivided into four units (Figure 2), despite of beds at the base of the succession are poorly exposed. However, in contrast, the units from mid-eudoxus Zone to the top of the formation that are well seen in the Formation. At the base of the formation until the eudoxus Zone, the strata are made up almost entirely of bioturbated shelly clays and in between beds, horizons of oil and bituminous are present. The upper part of the Eudoxus Zone until the upper Pectinatus Zone the composition is kerogen-rich mudstones and coccolith limestone.
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.
The site visited on this day was informally known as the Bedrock Knob (NTS grid reference: 120 342). It is in an area where patches of limestone and exposed bedrock are common. The bedrock is part of the Preca...
Sedimentary rock from the older Silurian Period is further from the river banks (Geological map of Victoria, 1973). Mudstone, inter-bedded shale and greywacke depositions indicate the Maribyrnong River may have previously taken a different shape, and younger sediments have replaced the older sediments in more recent geological periods.
To identify the specific type, functions and time period of the artifacts, various archaeology books, reports, and journal were referred. The interpretation was then conducted by dividing the artifacts into different area on the map and investigating their relationships.
The Powder River Basin is located in southeast Montana and northeast Wyoming. According to Luppens et al. (2008), the Powder River Basin is approximately 22,000 square miles in area. The basin itself trends in a north-to-north west direction. The eastern side of the basin dips gently westward, whereas the western side dips much more steeply towards the east. This forms an asymmetrical syncline with the synclinal axis lying closer to the western margin of the basin (USGS, 2013). The Powder River Basin is structurally separated from other basins by Laramide style tectonic landforms, where large portions of Archean basement rock were thrust upwards during the late Cretaceous and Paleocene (Flores, 2004). In Wyoming the Powder River Basin is surrounded by the Bighorn Mountains to the west, the Black Hills to the East, and the Laramie Mountains, Casper Arch, And Hartville Uplift to the South. To the north, in the Montana portion of the Powder River Basin, the Miles City Arch separates the basin from the Williston Basin in North Dakota. The coal beds that were deposited in the basin are mainly sub-bituminous but can also be lignite in rank and range from Cretaceous to Eocene in age. There are four formations that contain coal beds in the Powder River Basin and include the Mesaverde Formation, the Lance Formation, the Fort Union Formation, and the Wasatch Formation. Each of these formations contains several different coal ...
Plummer, C.C., McGeary, D., and Carlson, D.H., 2003, Physical geology (10th Ed.): McGraw-Hill, Boston, 580 p.
Basically these are the general features of the Earth and I am going to give you
The sharp differences in elevation between the Badwater Basin and the surrounding mountains that include the highest point in the continental US (Mt. Whitney at 14,494 feet) stand as a representation of the regions violent tectonic past. The mountains themselves are considered fault block mountain ranges meaning that they were formed when blocks of rocks were squeezed through the Earth's crust along parallel faults or were loosened from the crust when it separated at a fault. In the valley, both of these methods not only were the cause of the current mountains formation less than four million years ago, but also are causing the mountains to be uplifted while the valley floor drops even further. This phenomenon is one of the reasons why the lowest and highest points in the continental...
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.
"Sedimentary Rocks and the Rock Cycle." South Carolina Geological Survey, n.d. Web. 2 Dec. 2013.
As a result of this process, the mine sites "do not develop normal soil structure or support the establishment of a plant cover". Many mine sites have...