Exam 8: Time and Geology

An angular unconformity is an erosion surface that is tilted from the horizontal.

Earth is between 1 and 2 billion years old.

The principle of ___ states that an original sedimentary layer extends laterally until it tapers or thins at is edges.

Half life is the time it takes for a given amount of a radioactive isotope to decay to half its original amount.

A formation is the process by which sedimentary rocks come into existence.

In the radioactive decay process of electron capture a(n) ___ in the nucleus captures an orbiting electron.

____ dating uses the effect of neutron radiation coming from deep space to date material at Earth's surface.

An index fossil is a fossil from a very short-lived, geographically widespread species known to exist during a specific interval of geologic time.

The principle of superposition states that within a sequence of undisturbed sedimentary rocks, the layers get younger going from bottom to top.

Carbon-14 is created in the atmosphere by the nuclear reaction of neutron from the cosmic rays and _______ in the atmosphere.

Geologists use fossils in sedimentary rocks to assign their correct place in geologic history.

The principle of _____ allows rock layers in different places to be correlated on the basis of their fossils.

In a(n) __________ the erosional contact represents missing rock strata and separates sedimentary beds that are parallel.

The ___ of a radioactive material is the time it takes for a given amount of radioactive isotope to be reduced by half.

The _____ ended with the greatest mass extinction ever to occur on Earth.

The carbon-14 isotope disintegrates radioactively with a half-life of ______ years.

The truncation of bedding where sedimentary rock layers abut a granite pluton suggests a(n) ______.

The proportional amount of atoms that decay with time is only influenced by pressure and temperature.

Uranium-238 ultimately decays to _____ -206.