|
|
GEOLOGIC TIME
CHART
|
Relative Age Dating Terminology |
|
|
|
Eonothem |
Erathem |
System |
Series |
Cities and towns
in Texas
where
geologic units of different ages are
located. |
|
Absolute Age Dating Terminology |
Began |
|
Eon |
Era |
Period |
Epoch |
years ago (in millions) |
|
|
Cenozoic |
Quaternary |
Holocene (Recent) |
0.01 |
Galveston,
Port Aransas |
|
|
Pleistocene |
1.8 |
Brownsville, Houston |
|
|
Tertiary |
Pliocene |
5.3 |
Amarillo, Beeville, Lubbock, San Diego |
|
P |
Miocene |
23.7 |
Jasper, Brenham, Freer |
|
h |
Oligocene |
36.6 |
|
a |
Eocene |
57.8 |
Alpine, Canton, Laredo |
|
n |
Paleocene |
66.4 |
Mexia, Texarkana |
|
|
Mesozoic |
Cretaceous |
(See Details) |
144 |
Austin, Dallas, Sonora, Glen
Rose, San
Antonio, Terlingua |
|
e |
|
r |
Jurassic |
|
208 |
No significant exposures at the surface. |
|
o |
Triassic |
|
245 |
Colorado City, Post |
|
z |
Paleozoic |
Permian |
|
286 |
Abilene, Pine Springs,
Wichita Falls |
|
o |
Carboniferous |
Pennsylvanian |
|
320 |
Brownwood, Graham |
|
I |
Mississippian |
|
360 |
Mississippian age rocks are found near
Marathon and Llano. |
|
c |
Devonian |
|
408 |
Marathon: Rocks of these ages are not
differentiated in Texas. |
|
|
Silurian |
|
438 |
|
|
Ordovician |
|
505 |
|
|
Cambrian |
|
570 |
Mason |
|
Proterozoic |
Precambrian |
Vendian / Ediacaran |
|
600 |
|
|
|
|
2,500 |
Llano: No fossils in igneous rocks but
1.9 billion years old is cool. |
|
Archean |
|
|
3,900? |
Not present in Texas. |
|
Hadean |
|
|
4,6000? |
Not present in Texas. |
|
Earth forms |
|
|
4,6000? |
Texas will eventually exist. |
|
This chart is base on absolute age dating
techniques. Relative age dating uses
chronostratigraphy to date rock sequences
and does not adhere absolutely to the time
intervals listed. The terminology for each
technique is presented for comparison only.
When you look at a geologic map of Texas, the color of each Period/System
will aid in locating the
cities and towns. |
 |
|
|
|
|
