What is layers of sedimentary rocks?

Answer 1

Sedimentary is an adjective referring to material deposited by water, wind, or glaciers. Sedimentary rock covers a large part of the surface area of the continents. However, they are the "topping" and as they do not go deep in terms of the depth of the planet, they do not make up a large percentage of the total rocks, the three main kinds of rocks being sedimentary, igneous, and metamorphic. The three main types of sedimentary rock are clastic, biogenic or organic, and chemical or precipitate. After the sediments are deposited they build into layers. This is called lithification. Eventually they will form into rock if certain conditions are met. This process is known as diagenesis. As the question makes note of, they tend to form in layers, one atop the other. Sediments can be formed during a long time, such as shells or silt at the bottom of a lake or more quickly during floods. Sedimentary rocks usually have a high Calcium content, which acts as a form of cement, thus making each layer more solid. Chalk, limestone, sandstone, and shale are examples of sedimentary rock.

Limestone can be biogenic or chemical.

Coal is an example of biogenic sedimentary rocks.

Halite and gypsum are precipitate or chemical sedimentary rocks.

Igneous rocks are formed from volcanic eruptions.

Metamorphic are formed from the other two (igneous and sedimentary).

Scientists who believe in evolutionism, in varied fields such as geology, Paleontology, and evolutionary Biology, interpret sedimentary rock layers as layers of sediment (usually silt, sand or sea shells) deposited over millions of years. They are so interpreted because layers in the same location contain increasingly complex life forms, reflecting how life is inferred to have evolved according to the Theory of Evolution. Sedimentary rock layers can also be dated through the relative frequencies of certain isotopes, with older rocks at the bottom of the deposits.

Scientists who believe in Creationism, in the same variety of fields, believe they correspond to layers of sediment deposited by the Noachin (aka Noah's) flood and formed by the massive weight of the water.

Creationists do not accept the Earth being billions of years old, because they take the descriptions from The Bible literally and interpret the scientific data differently. They consider evolutionism as not explaining the abundance of fossils in the sedimentary layers as well as the flood does because fossils need quick burial to form. They consider that layers being laid down over a long period of time from erosion and other natural actions do not account for this as well as the the Noachin Flood does.

Both are theories and currently neither has been or can be proven scientifically. Both have anomalies. Both are plausible explanations unless an individual subscribes to one of the belief systems that disqualifies the other's explanation.

Since they are both theories, there are some who want Intelligent Design (belief that the universe was designed and created, although not necessarily by a god) to be considered as a plausible explanation as well as evolution in the teaching of science in schools. This movement claims that schools teach evolution as fact rather than theory thus necessitating the need for alternative explanations.

To go into the two systems of belief is beyond the scope of this answer to "What_are_the_Sedimentary_rock_layers". What they are I hope has been satisfactorily explained. How they formed is narrowed down to two main classes of thought, both with great minds putting forth excellent propositions. Anyone who wishes to investigate their formation should research Intelligent Design, Evolution, and Creation. When researching creation for something scientific as opposed to a moral or religious question, one should remember to concentrate on scientists, not preachers, to get the unbiased empirical data needed.