Banded Iron Formation Essay

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.

The author and his colleagues specifically chose to focus on 375 million year old rocks in their search for fossils because this was the time frame that provided fish that would be useful to study from. The 385 million year old rocks provided fish that look too similar to the ones we have now and the 365 million year old rocks have fossils that don’t resemble fish. The 375 million year old rocks, however, provide fossils that show the transition between fish and land living animals.

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

In order to find evidence of the transition from fish to land animals, the author and his colleagues chose to focus on 375 million year old rocks. In 2004, they studied sedimentary rock on Ellesmere Island in Canada’s Arctic as they thought that the rocks there would be exposed and untouched by humans, which would be ideal for fossil excavations. They studied sedimentary rocks (limestone, sandstone, siltstone and shales) because these

Deposition of sediments began in the basin during the Cambrian era, but subsidence and basin filling occurred the most during the Ordovician,

The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. It is also called the Age of Reptiles, a phrase introduced by the 19th century paleontologist Gideon Mantell .

Precambrian time is where things began to grow and form becoming an organism or recording earth’s history. Precambrian is the time of Bacteria and mechanisms such as plate tectonics. Also the formation of oceans and the atmosphere.

The geologic timescale comprises of Eons, Eras, Periods, Epochs and Ages, all of which fit into each other with Eon being the largest. Key geological events in the life of the planet are used to mark the transition from one of these chapters to another. Fig 1 has been created to illustrate where we currently are in the geological timescale and the dates and events that led us here.

The first super-continent- Rodinia broke up and vertebrate life began to colonize the planet. (Ross, Whitmore, Gollmer, Faulkner, 2015). This era is broken up into six time periods: the Cambrian- characterized by the sudden appearance of , Ordovician- characterized by life moving out of the oceans, Silurian- invertebrates appeared, Devonian-the first vertebrates appear, Carboniferous- when coal beds were formed around the earth due to “low-oxygen sedimentary conditions that produced peat” (Ross, Whitmore, Gollmer, Faulkner, 2015) and the Permian- when the extinction of most of the marine invertebrates

The Precambrian era does not have a previous era.But the era after the Precambrian was the Paleozoic. The Precambrian era was from 4.8 to 4.5 million years ago with the paleozoic era before it and then the Mesozoic era after. The time periods in the paleozoic era were Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Carboniferous, and Permian.The precambrian era did not have a previous Geologic era. The precambrian era had different periods which are Proterozoic, Archaean, and Hadean my major climate was the the ice age.my main geologic period was formation of earth and life for an example plants.The continents that the precambrian era had were pangia, animals that lived in the geologic era was waptia Dickinsonia protozoa

The oxygen revolution: During the Proterozoic, biotic system were being established, which gave rise to biomass of the prokaryotic organisms like the “benthic and planktonic photosynthesizing organisms” Due to the vast developing diversity of environment, organisms could well adapt to these various environments, which increased the input of oxygen on Earth. Hence, in order for the oxygen to be accumulated in the atmosphere, Iron and Sulfur like oxygen-sinks had to be depleted.

The Paleolithic Era or (Old Stone Age) started around 2.6 million years ago and ended 10,000 years ago. There were many human species in the Paleolithic era but only one species survived up until the Neolithic Era (New Stone Age). Paleolithic Humans

Multiple ways have been invented to test the age of fossils, from tephrochronology, which “uses chemistry and age of volcanic deposits to establish links between distant stratigraphic successions” to the use of deposited strata (Peppe and Deino). Tens of thousands of fossils have been excavated and more and more are dug up each year. In this debate on the origins of the earth, many people like to use fossils and the fossil record. “Fossils are precious gifts from the geologic past: signs and remains of ancient living things preserved in the Earth's crust” (Alden). For fossils to be formed they have to be taken out of a decomposing environment immediately, relatively

The oldest rocks exposed are arkosic sandstone and shale, and small amounts of thin-bedded chert and altered volcanic rocks, of the Upper Jurassic Franciscan formation. Large masses of serpentine and smaller plugs and dikes of gabbro and diorite intrude these sediments; glaucophane schists and their unusual mineralogical assemblages are developed locally. The series as exposed on the San Jose quadrangle consists chiefly of sandstone, shale, and jasper; with occasional bed of heavy conglomerate. Scattered here and there throughout its area are small patches of greenstone, probably of tuffaceous origin. In several localities it is associated with serpentine, eclogite, and diorite, each of which is supposedly intrusive into it. However, large areas of practically unaltered sandstone and shale exist in what is known

Even though anoxia is in general reflected on as an essential pre-requisite, “anoxia alone is not sufficient enough to account for Burgess shale-type preservation,” (Garson 2012). Furthermore, the necessity of anoxia is not universally agreed upon (Garson 2012). Yet, while rare and commonly absent from today’s fossil record, this type of preservation is very common throughout most Burgess shale-type deposits of these ancient fossils (Gaines 2012). Localities of these types are somewhat confined to Series 2 and 3 of the Cambrian (Garson 2012).