Measured or measurable duration; A non-material dimension of the universe,
representing a period during which an action or condition exists.
GEOLOGIC TIME:
The time extending from the end of a formative period of the Earth
to the beginning of human history; the part of the Earth's history recorded
in the succesion of rocks (the rock record).
GEOLOGIC TIME SCALE
An arbitrary chronologic arrangment of geologic events, commonly presented
on a chart
GEOLOGIC TIME UNIT:
A span of continuous time in geologic history, during which a corresponding
chronostratigraphic unit was formed.
GEOLOGIC TIME UNITS:
In order of decreasing magnitude:
Eon Precambrian
(88%) Phanerozoic (12 %)
Era
Paleozoic, Mesozoic, Cenozoic
Period During which rocks of
a corresponding system were formed. Fundamental unit.
Epoch
Age
Concepts
Relative versus absolute time (laundry pile versus alarm clock)
Geologic time scale: A relative time-scale based on stratigraphy
How can one tell geologic time?
Stratigraphic subdivisions
Lithostratigraphy
Biostratigraphy
Chronostratigraphy
Magnetostratigraphy
Stable-isotope stratigraphy
Geochronology: Science of absolute dating, often using radiometric
dating
