An isotope is a species of the same element with the same mass and different atomic number.
The principle which states that “in layered rocks (or strata) the oldest rocks are at the bottom and the younger layers are on top” is the principle of _______.
______ refers to the number of protons of an atom.
atomic number
In a succession of strata, fossil species succeed one another in a definite and recognizable order.
The short half-life of carbon-14 limits the use of this technique to generally dating materials less than _______ years old.
50,000 – 60,000
Disturbed rocks or strata are ______ those rocks that disturb or cut through them.
older than
Particles that settle under the influence of gravity settle to more nearly vertical layers.
In a succession of strata, fossil species succeed one another in a definite and recognizable order. This order of appearances and disappearances is largely the consequence of _______.
all of these (organic evolution, the extinction of other species, and the appearance of new species)
The principle which states that “strata extend in all directions until they thin against edges of the basins they accumulated in” is the principle of _______.
original lateral continuity
The original continuity of strata in a basin can be broken. A river can carve a canyon into a basin leaving once continuous layers stranded on opposite sides of the canyon. According to the principle of lateral continuity, these opposite sides of the valley were once laterally continuous.
This type of unconformity separates horizontal sedimentary rocks above and below the unconformity.
Radiometric age dating, the basis of the establishment of the absolute geologic time scale, was not possible until after the discovery of radioactivity in the 20th century.
Based upon physical characteristics alone (not fossil characteristics), which type of hiatus would be most difficult to identify?
Radioactive decay is the spontaneous nuclear disintegration of isotopes at ________ rates.
_______ is the sum of protons and neutrons in the nucleus of an atom.
atomic mass
Which of the following is the oldest?
lower creatceous
History is a sequence of events placed in proper chronological order.
Which of the following is not a geologic period in the Mesozoic Era?
The basic rock unit defined on the basis of distinctive and easily recognized characteristics is a _______.
The principle which states that “disturbed rocks or strata are older than those that cut or disturb them” is the principle of ________.
cross-cutting relationships
The ______ is the product of placing rocks in their proper sequence of formation to create a composite record of geologic events.
relative geologic time scale
A horizon between rocks or sediments with distinctly different ages is called a ________.
Which of the following is not a type of unconformity?
Radiometric age dating techniques were used to establish the relative geologic time scale.