Chrononstratigraphy and Geologic Time Units (Geochronology)

Question 1

What is Chronostratigraphy?

Answer 1

Establishing the time relationship among rock units

Question 2

What is Geochronology?

Answer 2

Stratigraphic units defined and delineated on the basis of time

Question 3

The north american stratigraphic code and the International Stratigraphic Guide recognizes two funadamental types of geologic units. What are they?

Answer 3

Chrostratigraphic units and Geochronologic units

Question 4

What is a full defintion of Chronostratigraphy?

Answer 4

It is the establishment of time relationships among rock units. It is based on understanding the temporal (time) arrangments of rocks relative to one anoter. It gives older/younger relationships withut numerical dates

Question 5

What are boundaries of Chronostratigraphic units defined by?

Answer 5

On the basis of observable paleontological, physical, or chemical features of the rocks

Question 6

Name the various Chronostratigraphic units:

Answer 6

Eonothem, Erathem, System (The fundamental unit of Chronostratigraphy), Series, Stage, and Chronozone

Question 7

What is an Eonothem (1)?

Answer 7

The highest chronostratigraphic unit. Only three are recognized: the Archean, Proterozoic, and Phanerozoic eonothems

Question 8

Erathem (2)?

Answer 8

Subdivisions of an eonothem. None in the Precambrian. Three in the Phanerozoic

Question 9

System (3) ?

Answer 9

The primary chronostratigraphic unit of worldwide major rank. It can be subdivided into subsystems or grouped into supersystems, but most commonly subdivided into series

Question 10

Series (4)

Answer 10

Subdivision of a system. Commonly divided into 3 series. Such as lower middle or upper (example: Lower Jurrasic Shales)

Question 11

Stage (5)

Answer 11

Smaller scope and rank than series. Useful for intraregional and intercontinental classification and correlations. Many stages are recognized world wide

Question 12

Chronozone (6)

Answer 12

A nonhierarchial but commonly small stratigraphic unit. Its boundaries may be independent of those of ranked stratigraphic units

Question 13

Is a geochronological unit a stratigraphic unit.

Answer 13

No. However, it corresponds to the time span of an established chronostratigraphic unit

Question 14

What is a geochronologic unit?

Answer 14

Divisions of time traditionally distinguished on the basis of the rock record as expressed by chronostratigraphic units

Question 15

What are the various geochronolgical units?

Answer 15

Eon, Era, Period, Epoch, Age, Chron

Question 16

What is the Geological Time Scale

Answer 16

A means of classifying rocks on the basis of time. It helps to establish the relative ordering of events in earths history. Geologists use two difeerent frames of reference when discussing time: Relative and Absolute

Question 17

Relative age dating:

Answer 17

Involves placing geological events in a sequential order as determined from their position in the geologica record. It does not tell us how long ago an event occured, it just tells that one event preceded another. Uses the principals of stratigraphy

Question 18

ABSOLUTE AGE DATING

Answer 18

Absolute dating results in specific dates for rock units or event sexpressed in years before the present. Radiometric dating is the most common way to obtain absolute ages