Geology Midterm
Briefly, what is a biozone and what is its significance?
A biozone is the basic unit for biostratigraphic correlation, and a body of rock deposited during the time interval when an index or key fossil organism exists. It is significant because it can help determine the ages of rocks.
Briefly describe Alabama's Paleozoic fossil record, both land and marine fossils.
A common fossil in Alabama is invertebrates and vertebrate marine and non-marine organisms. Some examples are Stromatolites, trilobites, corals, and crinoids.
Does Alabama have any Archean bedrock? If not, what age of old bedrock lies beneath part of our state?
Alabama has Limestone bedrock from about 2.5 million years ago.
Briefly describe the fossil record for Cambrian and Ordovician in Alabama. Mention specific fossils by name and other details like locations.
Cambrian: dates back 541 million years ago, Olenellus in sandstone, stromatolite preserved in chert, algal laminations in chert Ordovician: 485 years ago, bentonite bed in limestone, brachiopods, graptolite fossils in shale
Take a look at the paleogeographic maps for Cambrian and Ordovician and describe where Alabama was during those times. Then, mention how the types of marine fossils relate to the ancient Alabama environment of those times.
During these times Alabama marine life was forming. For example, the Cambrian explosion of life went on and lots of different species came from that.
Take a look at the paleogeographic maps for Mississippian and Pennsylvanian and describe where Alabama was during those times. Then, mention how the types of land and marine fossils relate to the ancient Alabama environment of those times.
During this time bigger animals are starting to form like alligators. There were also insects that were found such as dragonflies and other insects. This was also a time known for coal-forming swamps.
What may have been the effect(s) of the great oxygenation event for life on Earth?
During this time the oxygen levels started to rise and the oceans got more shallow. This lead to the growth in minerals and elements on Earth that we now see and have today.
Pick out one of the Ediacaran fauna, name it, and discuss what it may have been and how it lived during Neoproterozoic.
I chose Charnia and when looking at the picture it looks like a fossil from something you would find in the ocean. It reminds me of sea plants and coral. This was found in northern Russia, Siberia, and Newfoundland. I think it lived under water for a long time.
Briefly describe the fossil record for Neoproterozic. Mention specific fossils by name and other details.
In this period of time there were three great continential glaciation. There was a breakup of the supercontinent Rodina and the formation of Panntoia. There were Metazoans which is multicellular animals with soft bodies.
When (how long ago) were the five great mass extinctions of life on Earth?
Late-Cambrian: 485 million years ago. Late-Ordovician: 440 million years ago. Late-Devonian: 365 million years ago. End-Permian: 250 million years ago. End-Triassic: 210 million years ago. End-Cretaceous: 65 Million Years Ago.
How might life have developed and where might it have developed on Earth during Archean?
Life developed from the comets and asteroids that stroke the Earth. They also form from waters such as the ocean and lakes.
Briefly describe the fossil record for Mississippian and Pennsylvanian (marine and land). Mention specific fossils by name and other details like locations.
Mississippi: time of the "sea lilies", early carboniferous, amphibian abundant, crinoids abundant Pennsylvanian: late carboniferous, land animals, there were millipede prints in Kansas, insect larva traces in shale,
Briefly describe the fossil record for Silurian and Devonian. Mention specific fossils by name and other details like locations.
Silurian: 443 million years ago, red mountain formation, red beds in limestone, sponge fossils Devonian: 419 million years ago, lycophyte, reef formers, stromatoporoid, brachiopads
Briefly describe the fossil record for Mesoproterozic. Mention specific fossils by name and other details.
Some examples of organisms is Horodyskia, and that is a fungi that was found in a Glacier National Park in Montana. The Grand Canyon played a big role in this period of time. There were supergroups in the Grand Canyon with sandstones, siltstones, and shales.
Briefly describe what is a stromatolite and what is the significance of the symbiotic relationship that existed (and still exists) in these odd structures. How did they change the atmosphere during Archean?
Stromatolite is a sediment structure built by cyanobacteria living in concert with bacteria. Precambrian Stromatolite were close together whereas modern stromatolite is spaced out.
About when did the "explosion of life" occur and what percent of geological time had already passed by the time this "explosion" occurred?
The "explosion of life" occurred 541 million years ago About 10% of the geological time scale had passed by the time the explosion occurred.
What are the time spans for the Hadean and Archean and what were the main events in this early span of Earth history?
The Archean began 4 billion years ago and ended 2.5 billion years ago. The Hadean began at the formation of planets which was 4.6 billion years ago and ended 4 million years ago. The important events for Hadean were the formation of the Earth's core and the moon. The important event for Archean is the Cataclysmic Bombardment of the Earth and Moon.
In a few sentences, how is the geological time scale related to the history of life on Earth (the fossil record)?
The Geological Time Scale relates and is important because it maps out the history of Earth into different sections such as eras, periods, eons. By having this, this can give us an idea of the ages of fossils and rocks. Without the time scale, figuring out the ages of fossils and overall chronological map of the Earth would be impossible.
Of the readings in the Encyclopedia of Alabama, which article or topic interested you the most? Briefly summarize this article and the things you found most interesting in it.
The article that interested me the most was the Physiographic Section because it listed all of the provinces and talked about what each one contained. For example, the Valley and Ridge province has diverse Paleozoic sedimentary rocks that are found in the northeast-southwest region.
What are the main biotic groups that appear as fossils during Archean?
The earliest form of life was found as fossils in sedimentary rocks. To be more exact in the Apex Chert. They were just microscopic prokaryote cells.
What ages of rock are not found in Alabama at all or are only found below the surface?
The rock that is only found below the surface is bedrock. That is one that age is not found because it is hard and solid and beneath the surface. This is also known as an igneous rock.
Briefly describe the main physiographic provinces of Alabama.
There are five physiographic provinces defined by the United states and those are, Cumberland Plateau, Highland Rim, Valley and Ridge, Piedmont Upland, and East Gulf Coastal.
What ages of rock are exposed on the surface in Alabama and in what provinces are the different ages of rock exposed on the surface?
They are exposed in a range from 2.5 billion years ago to 1,800 years ago. And the province was the Appalachian Valley and Ridge.
What factors favor fossil preservation of some part or trace of a dead organism?
They must have preservable parts like bones, shells, teeth, and wood. The must be buried by sediment to protect from decaying. And lastly, they should be physical, chemical, and biological indestructible after their burial.
Briefly describe the fossil record for Paleoproterozic. Mention specific fossils by name and other details.
This is an era where during the Paleoproterzic there was a supercontinent formed called "Nuna." During this time there was glacial deposits and asteroid impacts. Some examples of fossils are the Gunflint Chert which was from a microbial structure.