Lab 2 - Geo Time & Absolute Dating - F23
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School
New Jersey Institute Of Technology *
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Course
342
Subject
Geology
Date
Dec 6, 2023
Type
Pages
2
Uploaded by zxcv198
Laboratory 2
Geologic Time and Absolute Dating
CE 342 - Geology
Fall 2023 -
Dr. John Schuring
1)
Dating the Rocks in the Newark and NYC Metro Area -
Examine the geologic events in the
stratigraphic section below, which is in our own geologic backyard!
You are going to
“
date
”
selected
rock formations using the principles of absolute dating.
Radiometric analysis has been performed for five samples extracted from the rock beds shown
on the section (see next page).
The results of the chemical assays are shown in following table.
For
the purposes of this analysis, assume that the mass of the initial daughter isotope is negligible.
Show
all calculations!
Sample
Location
Formation Name
Parent Isotope
Type/Mass
Daughter Isotope
Type/Mass
Glacial B
Glacial Lake Deposits
C
14
/ 20g
N
14
/ 22g
Metamorphic A
Manahttan Prong
CZm
Manhattan Schist
Ru
87
/ 20g
St
87
/ 1g
Sedimentary A
Newark Basin
Trs
Stockton Formation
Po
40
/ 65g
Ar
40
/ 32g
Sedimentary B
Newark Basin
Jkp
Passaic Formation
Po
40
/ 63g
Ar
40
/ 27g
Intrusion A
Newark Basin
Jd
Diabase (Palisades Sill
Po
40
/ 64g
Ar
40
/ 22g
In addition to estimating the date, you will also:
A.
Name the Era/Period/Epoch for each sample from the Geologic Time Scale based on the
computed date.
B.
Now cross-check the Era/Period/Epoch with the one listed under the
“Formation Name” from
the 1:250,000 Bedrock Geologic Map posted on Canvas (all except Glacial B).
Also, provide
the lithologic and textural description of the formation from the 1:250,000 map.
C.
Create a master table summarizing all the above results listing the formations in order of age
from youngest to oldest.
NJIT Campus
5 mi.
2)
Geo Time Scale Graphic
–
You are going to
create a “pie
diagram
” representing the
entire geologic history
of Earth.
The 4.6 billion year timeline will appear around the circumference of the circle beginning at the top of
the pie with the present day (0 BP) and then running counter-clockwise to the top again (4.6 billion BP). Note
that BP = Before Present.
For maximum credit, the Time Scale should be drawn to scale in CAD.
First you will create the
“
major slices
”
of the pie according to the eons and eras that have occurred, including:
Cenozoic, Hadean, Paleozoic, Mesozoic, Proterozoic, and Archean.
Make sure to label the year at the boundary
between adjoining time periods.
Next you will label the specific events in Earth’s history with “leader lines” around the ou
tside of the pie. These
events include:
•
Oldest rocks (4.0 billion years BP)
•
Blue-green algae begin producing atmospheric oxygen (2.9 billion years BP)
•
Manhattan Schist under NYC is formed (1.2 billion years BP)
•
Trilobites appear in ocean
–
first complex life (570 million years BP)
•
First land plants (390 million years BP)
•
Supercontinent Pangea breaks apart (200 million years BP)
•
Tyrannosaurus Rex walks the Earth (68 million years BP)
•
Dinosaurs become extinct (65 million years BP)
•
Ice Ages begin (2 million years BP)
•
Homo Sapiens emerge
–
That’s us! (250,000 years BP)
•
Giant mammals become extinct (10,000 years BP)
•
Fall of the Roman Empire (1,545 years BP)
Finally, comment on what is immediately apparent about the distribution of our knowledge of Earth history
from the pie diagram.
Why is this the case?
DUE TUESDAY, SEPT. 26
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