The answer is "Because index fossils only existed for a short time, they can be used as a marker to identify the time period of a rock layer."

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries.

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
Convergent: compressional; plates move toward each other.
Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

The answer is convergent.

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries. 

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
Convergent: compressional; plates move toward each other.
Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries. 

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
Convergent: compressional; plates move toward each other.
Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust. Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries. 

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
Convergent: compressional; plates move toward each other.
Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust. Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries. 

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
Convergent: compressional; plates move toward each other.
Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

The answer is "a volcano."

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.

Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries.

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.

Convergent: compressional; plates move toward each other.

Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well

The answer is "Plate A and Plate B will move away from each other. It is a divergent boundary."

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.

Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries.

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.

Convergent: compressional; plates move toward each other.

Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

The answer is "a divergent boundary."

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.

Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries.

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.

Convergent: compressional; plates move toward each other.

Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.

The answer is "earthquakes."

Earth’s crust, also called the Lithosphere, is divided into tectonic plates. These plates move at plate boundaries due to the liquid hot mantle beneath the crust.

Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth's geologic activity takes place at plate boundaries.

Divergent: extensional; the plates move apart. Spreading ridges, basin-range.

Convergent: compressional; plates move toward each other.

Transform: shearing; plates slide past each other. Strike-slip motion.

At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. Convergent boundaries create mountains, and transform boundaries cause earthquakes as well.