Chapter 23

Question 1

Paleozoic era

Answer 1

The time of ancient life from about 543 million years ago to 248 million years ago

Question 2

Pangaea

Answer 2

The late Paleozoic supercontinent made up of Gondwanaland and Laurasia

Question 3

Unconformities

Answer 3

Time gaps in the rock record caused by erosion of pre-existing rock or by an interruption in the sequence of deposition

Question 4

Crosscutting relationships

Answer 4

And igneous intrusion or fault that cuts through pre-existing rock is younger than the rock through which cuts

Question 5

Relative dating

Answer 5

The ordering of rocks in sequence by their comparative ages

Question 6

Precambrian time

Answer 6

The time of hidden life which began about 4.5 billion years ago when earth formed, lasted until about 543 million years ago

Question 7

Lateral continuity

Answer 7

Sedimentary layers are deposited in all directions over a large area unless some sort of obstruction or barrier limits their deposition. Faulting, folding, and erosion can separate originally continuous layers into isolated outcrops

Question 8

Superposition

Answer 8

In an undeformed horizontal sequence of sedimentary rocks, each layer is older than the one above and younger than the one below. Like the newspapers in a recycling bin, all the papers are found below newer, more recent papers

Question 9

Radiometric dating

Answer 9

A method for calculating the age of geologic materials based on the nuclear decay of naturally occurring radioactive isotopes

Question 10

Cenozoic era

Answer 10

The time of recent life which began 65 million years ago and his ongoing. Also known as the age of mammals

Question 11

Faunal succession

Answer 11

Fossil organisms follow one another in a definite, irreversible time sequence. Fossil communities change through time at some species become extinct in new ones up here. Such changes are reflected in the rock record. In this way, fossils provide a key to for recognizing the relative ages of rock

Question 12

Mesozoic era

Answer 12

The time of middle life, from about 248 million years ago to 65 million years ago. Also known as the age of the reptiles

Question 13

inclusions

Answer 13

Inclusions are pieces of one rock contained within another. Any inclusion is older than the rock containing it just as small pieces of rock Inc. in a slab of concrete or formed before the concrete was formed

Question 14

Original horizontality

Answer 14

Layers of sediment are deposited horizontally. layers that are tilted or fold must have been moved into that position by disturbances such as earthquakes and mountain building, after deposition