What Are The Four Distinctive Eras

Approximately 17 meters thick, Unit A defines the lowest third of the Juniata Formation. Fragments of marine fossils, including bryozoans, brachiopods, and gastropods, are commonly found in the bottom-most portion of this unit of structureless mudstone and quartz arenite. Quartz grains in the sandstone beds of Unit A are typically immature and fine-grained, though the sandstone packages tend to coarsen upwards. Though typically structureless, intermittent bedding of the sandstone and shale packages is observed in this unit, and some areas display

Paleolithic: The Paleolithic period lasted from about 200,000 b.c. to about 10,000 b.c. It was the early phase of the Stone Age; and encompassed a steady development of stone tools, antler and bone artifacts, engraving on bone and stone, and paintings on the walls of caves and rock structures. There was not much structure built or agriculture done in this period as the people lived a nomadic lifestyle, migrating with the herds of animals they hunted for food.

Florida and Shenandoah National Park have many commonalities as well as differences that makes each of these geologic setting unique. Though North America looks like Florida and Shenandoah National Park never seemed to collide with one another, Shenandoah has a rock record of being about 1 billion years old that constructed the North American continent and a building block that formed the Appalachians through orogenies. Florida falls about 300 million years old with the North American plate, however findings that were part of Gondwana provides evidence of the origin of Florida. With a vast time difference of these rock records, what can be furthered analyzed of what the

One of the major things noticeable from the cross section is that quite a few of the rock layers are over turned, where the older rock layers are above the newer rock layers. This is seen in the contact between the Quartz Monzonite of Papoose Flat and the Campito Formation which is also a disconformity. Next there is some fault zones separating the Camptio, Poleta, and Harkless formations. We then see some more overturned layers with the contacts between Saline Spring Valley Formation (lower and upper members) above the Mule Spring Formation along with some inferred folding. With a normal fault separating the inferred folding event, we see where the overturning occurs. In between the Cambrian layers we see Tertiary Basalt nonconformities also being folded, thus with that we know that the folding event was more recent than the formation of the Basalt. Next there is a large Basalt field with a spot of the Harkless formation. Again we see over tuning as the Basalt field ends there are the Devonian and Mississippian rock Layers on top of the basalt. Separating these overturned layers from the Harkless Formation and the Saline valley Formation (upper member), which are not overturned, is a thrust fault. From this information, there was a major stress event sometime after the Tertiary period causing the rock layers to fold and overturn. And from this stress event and from the folding, normal and thrust faults are formed. Finally we see that there were alluvial and landslide deposits from the Quaternary after the folding, faulting, and over

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The quadrangle is considered to be a part of the Allegheny Plateau, so the rocks in this region are mostly of Carboniferous age. Carboniferous rocks are subdivided into two series: the Pennsylvanian and Mississippian. The rocks of both series mainly consist of alternating beds of shale and sandstone, but Mississippian rocks on southern parts of the plateau include thick limestones (Phalen 1). Both series are represented in the Johnstown quadrangle. The Pennsylvanian series, however, covers most of the region, while Mississippian rocks appear only at the surface along deeply eroded anticlines.

I chose the Jurassic period; because this time enclosed mainly marine deposits such as shale, sandstone and limestone. There were a diversity of fossils found from this period which was only found west of the Mississippi River.

The Cambrian Period marks the beginning of the Paleozoic Era. This period gets its name from a place in Wales where the first examples of this type of ancient life was found. The period lasted for nearly 53 million years, from about 543 million years ago until 490 million years ago. The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears. It was once thought that the Cambrian rocks contained the

The basement rocks in the western Slave carton is older than 2.8 Ga and the known oldest rocks are the genesis found along the Acasta River which is about 3.6- 4.0 Ga old, which is estimated using the zircon dating (Isachsen & Bowring, 1994; Padgham,1992). Following by 2.8 - 3.5-Ga old genesis of Point Lake and genesis under the Yellowknife Greenstone belts, which exist over 3 Ga (Isachsen & Bowring, 1994; Padgham,1992). The major rock types include granitic to tonalitic genesis, migmatitic genesis and granodiorites, which have been deformed and metamorphosed (Fyson & Helmstaedt, 1988; Isachsen & Bowring, 1994; Padgham,1992). In the eastern Slave Craton, the basement is not confined but is correlated to the Nd-Pb isotopic boundaries

Within every decade there are peaks and valleys which define how the era is remembered. Each decade is remembered for different things, such as the 1900’s being remembered for the invention of the airplane and the beginning of silent movies. While the 1950’s remind people of recovering from war, a new symphonic style of music, and the launch of Sputnik 1, it also brings back memories of the Korean War, McCarthyism, and the beginning of decolonization in Asia and Africa. The 60 's are often recalled as being the era that the Cold War heated up along with John F. Kennedy, Martin Luther King, and the 70’s as the “hippie” decade. The positive and negative events of each decade leave some more memorable than others, a classic example of

I believe that we don’t need the ERA. During our debate I was part of anti-ERA group. As the intense debate ended my views didn’t change. I did learn a lot more by spending time researching the topic. By doing all of the research it made it more clear to me that we don’t need to the ERA.

Interval of geologic time lasting from approximately 66 million to 2.6 million years ago. It is the traditional name for the first two periods in the Cenozoic Era (66 million years ago to the present). The Tertiary has five principal subdivision, called epochs,which from oldest to youngest are the Paleocene (66 million to 55.8 million years ago), Eocene (55.8 million to 33.9 million years ago), Oligocene (33.9 million to 23 million years ago), Miocene (23 million to 5.3 million years ago), and Pliocene (5.3 million to 2.6 million years ago). During the Tertiary period, the compressional phase of intraplate tectonism transformed Texas west of the Pecos River into a dynamic landscape studded with scores of volcanoes. The peak of this volcanic

The study marks the first time that researchers were able to compare historical and geological records from the same cave in one place. In addition to recording the cave wall inscriptions telling the centuries-long climate change story, researchers removed sections of the formations in the cave and analyzed the elements and isotopes found inside them. What they found was that periods of drought had strong correlations to large concentrations of certain elements in the fragments.

Jurassic is a period of time with Dinosaurs, rodents and birds. There were also island seas consisting of sharks, sea monsters and blood-red planktons. The existing plants in that period were cycads, ferns and conifers. The Mesozoic era was about 245 million years ago to 65 years ago, so it almost lasted about 180 years in total. The Mesozoic era is divided into three periods of Triassic, Jurassic and Cretaceous. Mesozoic era means middle animals and it is the era, which the word’s fauna has changed from what is in the Paleozoic era and the most famous organisms of this era are dinosaurs. In the Mesozoic era, the extinction of more than 90 percent of species in the earth was observed and the reason behind it was mostly volcanic eruptions and climate changes. On the other hand, this era had massive changes that represented ecological niches and rise to new creatures such as rodent-size mammals and first dinosaurs. In Triassic, which was the first period of Mesozoic, the mammals and first dinosaurs existed. Later than that, the second period was Jurassic, which giant shaped dinosaurs and other kinds of dinosaurs were developed. Besides that the first flowering plants and primitive birds, with long teeth appeared in that era as well.

These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaur’s fossils.