1.5 - Building the Geological Timescale

Question 1

List the subsections of the geological timescale from largest to smallest.

Answer 1

Eon
Era
Period
Epoch

Question 2

What Eon are we interested in?

Answer 2

The Phanerozoic

Question 3

What are the 3 eras in the Phanerozoic? List from oldest to youngest.

Answer 3

Paleozoic (541mya)
Mesozoic (252mya)
Cenozoic (60mya)

Question 4

List the periods in the Paleozoic from oldest to youngest. 6

Answer 4

Cambrian (541mya)
Ordovician
Silurian
Devonian
Carboniferous (Mississipian below Pennsylvanian) 
Permian (ends 252mya)

Question 5

List the periods in the the Mesozoic from oldest to the youngest. 3

Answer 5

Triassic (252mya)
Jurassic
Cretaceous (ends 60mya)

Question 6

List the periods in the Cenozoic from oldest to youngest. 3

Answer 6

Paleogene (60mya)
Neogene
Quaternary (now)

Question 7

List the epochs in the Paleogene from oldest to youngest. 3

Answer 7

Paleocene (60mya)
Eocene
Oligocence

Question 8

List the epochs in the Neogene from oldest to youngest. 2

Answer 8

Miocene

Pliocene

Question 9

List the epochs in the Quaternary from oldest to youngest. 2

Answer 9

Pleistocene (ends 11.8ka)

Holocene (starts 11.8ka and is current epoch)

Question 10

What is the rhyme to remember the geological timescale?

Answer 10

Can Our Students Do Crossword Puzzles To Justify Credit
PNQ
Please Excuse Our Mess, Preparing Popcorn Here

Question 11

What is stratigraphy?

Answer 11

Sequence of rocks on the surface of the planet

Question 12

What is lithostratigraphy?

Answer 12

Technique used where you group together different packages of sediments that you see in the field.
Boundaries do NOT have to be isochronous (of same age)

Question 13

What are the subdivisions/units of lithostratigraphy from largest to smallest? 5

Answer 13

Supergroup, group, formation, member, bed

Question 14

What is the basic mapping unit of lithostratigraphy?

Answer 14

Formation

Question 15

What is a group?

Answer 15

The grouping of adjacent formations, sharing some lithological characteristics or genesis (eg. appearance - rock type - environment)

Question 16

What is a supergroup?

Answer 16

A grouping of different groups of formations

Question 17

What is a member?

Answer 17

A subdivision of a formation; can be laterally discontinuous

Question 18

What is a bed?

Answer 18

A lithologically distinct horizon/layer

Question 19

What is an isochron?

Answer 19

A line of equal time

Question 20

Give an example of how sedimentary environments are dynamic over time.

Answer 20

Sea level fluctuations

Question 21

What is a regression?

Answer 21

Sea level fall (eg. due to ice sheets growing)

Question 22

What is transgression?

Answer 22

Sea level rise (eg. due to ice sheets melting)

Question 23

Describe what occurs in the Llandovery (early Silurian) transgression in the Welsh Basin (4 steps based on the diagram)

Answer 23

1) At peak of the Ice Age, Southern Ireland and Southern Britain were a single land mass with extensive land surface exposure
2) As the Ice Age ends, the ice sheets melt, sea level rises due to the influx of water back into oceans - now land has contracted as sea floods onto shallower parts of the land mass
3) Sea level continues rising - extensive coverage of land under water
4) Back to major landmass over Southern Ireland and Britain caused by tectonic events and uplift of the area
General: over time the land steps east showing transgression of water, will not be isochronous as it gets younger to east, fossil data allows us to say what is younger or older, transgrssion occurs

Question 24

What are the subdivisions of geochronology from largest to smallest?

Answer 24

Period, Epoch, Age

Question 25

What are the subdivisions of chronostratigraphy from largest to smallest?

Answer 25

System, Series, Stage

Question 26

What is geochronology?

Answer 26

The absolute age of rocks, mya, calculated by radiometric dating (decay of parent isotope to daughter isotope)

Question 27

What is chronostratigraphy?

Answer 27

It details the pattern of changes in Earth's history regardless of their compositions or properties (only include rocks of certain age eg. Silurian rocks and their boundaries are synchronous everywhere)(boundary of a system is in the same place even if the age changes) Time-rock units

Question 28

What are the boundaries for chronostratigraphy?

Answer 28

Isochrons

Question 29

Describe lithostratigraphic Correlation.

Answer 29

It goes across from outcrop to outcrop/core to core - try to correlate boundaries. It is traced out in the field They are correlated in cores on the basis of geophysical signals. Over shorter distances: unit defined likely to be same age throughout Over longer distances: could be older in one place and younger in another

Question 30

What is a diachronous unit?

Answer 30

Non-synchronous lower and/or upper boundary - lithostratigraphic unit