midterm

Briefly, what is a biozone and what is its significance?

A biozone is a body of rock deposited during the time interval when an index or key fossil organism existed. It is important because they are the basic unit for biostratigraphic correlation. Biostratigraphic correlation helps find out the geological age and position of the rock and the geological events and processes that relate.

What ages of rock are not found in Alabama at all or are only found below the surface?

Ages outside of Precambrian to Holocene

Briefly describe Alabama's Paleozoic fossil record, both land and marine fossils

Alabama's best known fossil is Basilosaurus Cetoides, which is a ancient toothed whale. The most common fossils are brachiopods, which look like seashells. Alabama also has dinosaurs such as Lophorhothon atopus and Appalachiosaurus montgomeriensis.

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?

An organic and sediment structure built by photosynthetic cyanobacteria or blue-green algae living in concert with bacteria. Stromatolites are more common in Proterozoic rocks than in Archean, perhaps reflecting the more common warm shelf environments during Proterozoic. However, laminated structures resembling stromatolites are present in 3.5‐billion‐year‐old Archean rocks of western Australia and 3.0‐billion‐year‐old Archean rocks of southern Africa. Earth's early atmosphere was strongly reducing and anoxic (lacked free oxygen or O2 gas), and probably consisted primarily of water vapor (H2O), carbon dioxide (CO2), nitrogen (N2), carbon monoxide (CO), hydrogen sulfide (H2S), and hydrogen chloride (HCl). Stromatolites are believed to have caused an increase in oxygen due to photosynthesis.

What factors favor fossil preservation of some part or trace of a dead organism?

An organism must live in a suitable environment to have favor for preservation. The most suitable environments are marine and transitional environments. An organism must also have preservable parts such as bones, shells, teeth, or wood, be buried by sediment to protect the organism from scavengers and decay, and escape physical, chemical, and biological destruction after burial.

Briefly describe the fossil record for Cambrian and Ordovician in Alabama. Mention specific fossils by name and other details like locations.

Cambrian fossil record includes trilobite fossils and brooksella. Ordovician fossil record includes cephalopod, brachiopods (lived on the seafloor), graptolite fossils, and many more.

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 the Cambrian period and the Ordovician period, Alabama was south of the equator. Seas covered most of the state, which explains the marine life fossils.

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 the Mississippian period and the Pennsylvanian period, Alabama was at the equator a little bit below it. During these times, we see a lot of forests, which explain the plant fossils during the Pennsylvanian period. A lot was still underwater which explains the marine fossils.

What are the time spans for the Hadean and Archean and what were the main events in this early span of Earth history?

Hadean is the informal interval of time between the end of accretion and the onset of Archean. Hadean's main events are the formation of Earth's core and formation of Earth's moon (Luna). Four billion years is the arbitrary boundary between Hadean and Archean. Archean began about 4.0 billion years ago and ended 2.5 billion years ago. Archean's main event is evidence of early life.

Briefly describe the fossil record for Mississippian and Pennsylvanian (marine and land). Mention specific fossils by name and other details like locations.

Mississippian fossil record includes corinoid (lived on the Mississippian seafloor), blastoid fossils, Bryozoan, shark teeth, and many more. Pennsylvanian fossil record includes fern tree impressions and other plant fossils, fossilized tracks, and more.

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.

Physiographic Sections of Alabama talks about the different physiographic sections of Alabama and why they are divided up in that way. It was interesting to me because I didn't know Alabama was divided into these sections and that they differed those ways.

Briefly describe the fossil record for Silurian and Devonian. Mention specific fossils by name and other details like locations.

Silurian fossil record includes lingula (a primitive brachiopod), other brachiopods, sponge fossils, Silurian fossils, trilobite impressions, and a Silurian eurypterid. Devonian fossil record includes many early Paleozoic sea creatures such as graptolites and trilobites, and many more.

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" happened during the Cambrian period, about 541 million years ago. About 87% of geological time had already passed when this occurred.

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?

The ages of rocks range from Precambrian to Holocene (2.5 billion to 1,800 years old). Cumberland is characterized by Paleozoic sandstone, shale, and limestone. The Highland Rim has Paleozoic limestone and chert. The Valley Ridge has Paleozoic sedimentary rocks. The Piedmont has faulted crystalline metamorphic and igneous rocks which are the oldest rocks in the state. The East Coastal Plain has Mesozoic and Cenozoic sediments.

What are the main biotic groups that appear as fossils during Archean?

The earliest evidence of life occurs in Archean sedimentary rocks. The main groups of biotic are fossil organic molecules and carbon isotopes, microscopic cells (prokaryotes), algal filaments, stromatolites (layered algal/bacterial growth mounds), and fossil prokaryotes and multicellular life.

What may have been the effect(s) of the great oxygenation event for life on Earth?

The effects could have been the cause of the expansion of acritarchs and other eukaryotes during Paleoproterozoic. Also, the oxygen buildup was the extensive accumulation of ferric iron oxide, which stained terrestrial sediments a rusty red.

When (how long ago) were the five great mass extinctions of life on Earth?

The five great mass extinctions of life on earth were the ordovician-silurian extinction (440 million years ago), devonian extinction (365 million years ago), permian-triassic extinction (250 million years ago), triassic-jurassic extinction (210 million years ago), and cretaceous-tertiary extinction (65 million years ago).

Briefly describe the fossil record for Mesoproterozic. Mention specific fossils by name and other details.

The fossil record for Mesoproterozoic consists of primitive fungi called Horodyskia.

Briefly describe the fossil record for Neoproterozic. Mention specific fossils by name and other details.

The fossil record for Neoproterozoic consists of trails, burrows, and other trace fossils, and Ediacara fauna (the first evolutionary radiation of multicellular animals). Types of Ediacaran fauna are discoidal, frondlike, and elongate. Some specific fossils are Cyclomedusa, Charnia, Eoporita, Nemiana, and others.

Briefly describe the fossil record for Paleoproterozic. Mention specific fossils by name and other details.

The fossil record for Paleoproterozoic consists of fossils of the gunflint chert, specifically Eoastrion, Eosphaera, Animikiea, and Kakabekia. It also consists of many different eukaryotes.

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 divides the earth's geological history into segments of time, like a timeline. It is divided in a way that shows where fossil records revealed important changes in animals and plants during those times, changes such as the appearance or disappearance of fossil species. The fossils can be used to recognize the approximate age of a unit and its place in the stratigraphic column.

Does Alabama have any Archean bedrock? If not, what age of old bedrock lies beneath part of our state?

The state's bedrock consists of limestone, sandstone, shale, and chalk.

Briefly describe the main physiographic provinces of Alabama.

There are five physiographic sections, three in the Appalachian Highlands Region (Piedmont, Valley and Ridge, and Cumberland), Upper Coastal Plain, and Lower Coastal Plain. There are. Each divided by their different elements such as rocks and terrain.

How might life have developed and where might it have developed on Earth during Archean?

There are many hypotheses that go into the formation of life. Some might believe the building blocks of life arrived by comets and/or asteroids striking the Earth, while others believe the building blocks of life formed in oceans or lakes as a result of external input of energy. It is believed that early life developed in water such as oceans and lakes or in the early Earth's volcanic vents or within the crust itself.

Pick out one of the Ediacaran fauna, name it, and discuss what it may have been and how it lived during Neoproterozoic.

s the simplest of all the Ediacaran fossils but is hard to interpret. It seems to have a saclike body, has no tentacles but may have a mouth. It is from the White Sea region, Russia.