Earth’s History and Geological Time

Variations among species are caused by adaptations because an organism of a species may differ from another in their traits. This means that in order to survive, different organism will develop certain things in order to reduce competition and increase their chances of survival.

The theory of Natural Selection is a theory that explains how some organisms of the same species, may be better adapt to survive than others.

An adaptation is a trait that is inherited, or passed down from one to the other, They allow the organism to survive based of it's specific environment and living patterns.

Five examples of traits/ adaptations are colour, camouflage, food gathering, sensory abilities, cartain behaviors, and other physical traits.

Adaptations can tell us certain things about organisms, such as what it ate, where it lived, how it moved, how it reproduced, and how it survived overall.

Fossils are the preserved remains or traces of a specific organism that lived in the past, or a time before ours. Fossils are mainly from less than 10,000 years ago and are often times found in sedimentary rock.

The six different types of fossils are mold, which forms when sediments bury an organism in multiple layers, as the organism decays, a cavity is left in the shape of it in the sediment; cast, which forms when a mold of a fossil is filled with sand or mud; carbonized, which forms when an organism is pressed in between layers, leaving an imprint in the rock; petrified, which forms when minerals soak in the remains and changing them into rock; preserved, which forms when an organism is prevented from decaying with tar, ice, rock, or amber; trace, which is formed when mud or sand hardens into stone where something left by the organism was.

The fossil record gives us farther information about the past life and environments that were on earth.

The fossil record can give us clues about the diversity of living and once living things, the past climate(s) on earth, and the changes that have occurred with organisms over time.

Absolute dating can be used for identifying the time frame in which an organism lived and died in.

The most common type of absolute dating radioactive dating. Radioactive dating is when radio isotopes within a substance are compared to those in the modern day.

Relative dating is the age of an object compared to the age of another object, although, this method cannot be used to tell the exact age of said object.

The law used to order rock layers as well as what identifies them to do so is the Law of Superposition. This is when each rock later gets older as more and more pile upon it. Therefore, the closer to the surface the rock layer it, the younger it is.

Index fossils help find the age or rock layers in which they are a fossil themselves. In order to be an index fossil you must qualify under certain requirements. These requirements are to have only lived in a small portion of earths history, to be found in multiple places, and to be a unique organism.

Trilobites are hard-shelled animals that lived in shallow water and seas. These organisms became extinct around 245 million years ago and are now a great example of an index fossil.

The geologic time scale divides the history of earth into different units of time. This scale began when the earth was created, which was around 4.6 billion years ago.

In order from least to smallest on the geologic time scale, the timeline goes supereon, eon, era, period, epoch, and age.

The Precambrian time was the earliest and longest lasting span of time in earths history. Some major events from this time was earths cooling, the formation of the crust, the first form of bacteria, and the oxygenation of the atmosphere.

The Paleozoic era means "old life." Many things developed during this area, mainly consisting of early land plants such as mosses or ferns, but by the end, seed plants were common. To end this era, what occurred was the largest mass extinction which ended up wiping out 95% of all organisms on earth.

The Mesozoic era means "middle life." The dominant animal from this time was various species of reptiles.

The Cenozoic era means "new life." Flowering plants became more common as this era progressed, and humans were introduced during this period of time.

How each era was divided up was mainly due to the organisms that were introduced/ became common/ died out during that time.

The Precambrian time time up the most of an era of earth. This era is around 88% of the geologic time.

The Paleozoic era is most known for the "Permian extinction", in which was a mass extinction that killed most marine invertebrate.

Paleontologists created a picture of common organisms from each time using the fossil record.

The major factors that were man made to cause extinctions were the cutting down of rain forests, the removing of habitats, pollution, and over harvesting.

The major natural factors to cause extinctions are volcanoes, global warming, global cooling, changes in oxygen, and impacts from asteroids/ comets.

Eruptions from a volcano can majorly affect a species because ash and dust can be sent high into the atmosphere and carried large distances around the earth, which causes respiratory issues for many species, as well as the ash and dust having the possibility of blocking out the sun for long periods of time which can easily disrupt the process of photosynthesis.

Asteroids and comets affected the times before us majorly because, although many would burn up in the earths atmosphere, many struck the earth before the atmosphere even developed, and one of a large enough size could easily pass through the atmosphere after it developed.

Climate changes are a condition on earth and are ever-going. They affected many periods of time by wildly changing the temperatures and land forms, as well as making organism adapt quicker and more wildly.