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Deposition of sediment with each new layer younger than the layer below is referred to as the princile of


In a sequence of rock layers we find fossils of trilobites and dinosaurs. The trilobite is at the bottom of he rock sequence in layer 1. The dinosaur fossil are found in layers 2, deiectly above the trilobite fossils. We conclude that

the processes of erosion have created a gap between the ages of the trilobite and the age of the dinosaur.

The principle of superposition states that the top layer of the rock is

the youngest

The scientific principle hat assumes that the different forms of animals throughout the Earth's past occurred in a definite order is called the principle of

faunal succession

Conditions for the preservation of fossils are best achieved

on the floors of shallow seas

The principle of faunal succession is based on the four assumptions of (1) the validity of the principle of superposition;

(2) the sequence of fossils are the same everywhere (3) rock layers of different ages will contain different types of fossils; and (4) the validity of the principle of original horizontality

The rather simple idea that,unless disturbed, younger sedimentary layerd overlie older layers, is referred to as the principle of


In a sedimentary rock that contains inclusions of metamorphic rock, the inclusions must be

older than the sedimentary rock

Uniformitarianism is the assumption that

present day processes also occurred in the geologic past

To date relatively young rocks and materials, we use the decay of

carbon -14 to nitrogen -14

To date the age of the Earth's, we look for rocks with a high percentage of

uranium-238 to lead-206

The Earth's age has been determined to be

4.5 billion years old by using meteorites

Radiocarbon datingis limited to the remains of plants and animals that died no longer than about

5700 years ago

If a radioactive element has a half-life of 704 million years, and the amount of parent material remaining is one-eighth of the original amount of parent material, the specimen is

2,112,000,000 years old

If the half-life of some radioactive element is 1 billion years, and a mass of rock originally contained 100 g of that element, how many grams of the radioactive element would be left after three billion years had passed

12.5 g

The isotope most useful for dating rocks from the late Pleistocene is


Life forms in the Precambrian include

stormatolites and certain primitive blue-green algae

The oldest known fossils are

algae and bacteria

You would expect to find the least number of fossils in rocks from the

Precambrian era

The Paleozoic era begains with he Cambrian and concludes with the

Permian period

The Ordovician period is most noted for the

great diversity in marine life

The formation of the supercontinent of Pangaea

resulted from the collision of all major land masses

The climatic zones of Pangaea ranged from

glaciation in the south, and a mild temperate climate in the north

Ancient geologic processes as revealed in Paleozoic rock layers were

very similar to processes of erosion and sedimentation

Life first started to flourish on Earth with organisms that were easily preserved as fossils about

543 million years ago

The high concentration of iridium at the Cretaceous Tertiary boundary is most likely attributed to

meteorite bombardment

The Mesozoic era is known a the age of the


Iridium is an element that is relatively

rare on Earth, but very common in meteorites

The Cenozoic Era is known as the

age of the mammals

Uplift of the Rocky Mountains was a result of

compressional forces

During the Pleistocene ice age

there were several episodes of glacial advance and retreat

In general, when we refer to the time of the "Ice Age" we are referring to the

Tertiary era

The extensive glaciation of the Pleistocene caused sea level to

drop because a great deal of water was bound in glaciers

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