Rocks Lab 3 - Student Handout
docx
keyboard_arrow_up
School
Colorado State University, Fort Collins *
*We aren’t endorsed by this school
Course
121
Subject
Geology
Date
Dec 6, 2023
Type
docx
Pages
6
Uploaded by BarristerSkunkPerson972
GEOL 121
Name _________________________________
Lab Section ____________
Rocks Lab 3 – Rocks of Colorado and Geologic Maps
Learning Objectives:
1.
Describe, Identify, and Interpret Rocks from Colorado
2.
Find information about the geology of a region from a geologic map
In this week’s lab, you will continue to practice your skills at describing and identifying rocks, this
time using rock samples from the Colorado Front Range. All of the rocks that you will see in lab
this week are rocks that you can see when you are out exploring around Fort Collins and in the
foothills. You will also use a geologic map to gain more detailed information about the rocks of
the Front Range.
Part 1: Rocks of the Colorado Front Range
For each unknown rock sample, you should provide:
1)
A detailed description. Your description should be detailed enough that someone
reading your description could easily pick out which rock you are talking about.
Your description should include information such as the rock’s color, texture, grain
size, minerals present, layering, fossils present, variability, abnormalities, etc.
2)
Whether the rock is igneous, sedimentary or metamorphic, and how you know.
3)
An identification of the rock.
4)
A hypothesis of how the rock formed and the evidence supporting your hypothesis.
Rubric for rock descriptions:
0.5 pt.
0.25 pt.
0 pt.
Descriptions contain enough detail that
someone reading the description could
picture the rock in their mind. Features such
as color, shape, texture, irregularities,
patterns, layering, grain size and shape,
minerals present, etc. are described when
appropriate.
Descriptions are given but lack
adequate detail to fully under-
stand what is being seen.
No response given.
Rocks Lab 3
GEOL 121
Sample #
Rock Description
Rock Type (ign, sed, or
meta)
How do you know?
Rock ID
Formation Hypothesis
And Reasoning
Sample 1
Spotted with black, pink
and silver
Igneous rock
Half of it looks Intermediate
Granodiorite
Medium to coarse
grained
Sample 2
The rock has a fine grainy texture
and the color of it looks gray and
black
Sedimentary rock
Reacted to acid
Calcareous shale
Reacted to acid
Sample 3
it has a coral color with white
specks all over
Sedimentary rock
Conglomerate
Has a lot of mineral
fragments
Rocks Lab 3
GEOL 121
2
Sample #
Rock Description
Rock Type (ign, sed, or
meta)
How do you know?
Rock ID
Formation Hypothesis
and Reasoning
Sample 4
Shiny red and gray colored flat
surface
Metamorphic rock
Recrystallization of fine grained
mudstone and shale
schist
It looked like shale and
mud stone
Sample 5
The rock has tiny sheets of black
and gray
Sedimentary rock
The rock has a softer fell with a
dusty texture
Shale
Has a dusty texture
3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Rocks Lab 3
GEOL 121
Part 2: Geologic Maps
Take a few minutes and examine the map that has been provided.
1)
What is this map showing you? What spatial area is this map showing? What do the colors
represent?
This map provides us
with an illustration of the
minerals that can be
found at Horse
tooth
reservoir and the time period they were formed
The map shows us an illustration of the minerals that can be found all around Horse tooth
reservoir and the time period they were formed
The different colors represent the different types of minerals
2)
In what area of the map do you generally find igneous and metamorphic rocks? In what area
of the map do you generally find sedimentary rocks?
Sedimentary rock can be found
near creeks at lower elevations
Igneous rocks can be found at body’s of water
Metamorphie rocks can be found at higher elevations
3)
Find the rock formation labeled Xbc on the map and in the legend.
What is the name, age, and
composition of the formation? Which of the rocks that you previously described best matches
the description for Xbc?
4
Rocks Lab 3
GEOL 121
Boulder creek Granodiorite, 1,660 MA, a light or darkish gray with medium grains
Calcareous shale
4)
Find the rock formation labeled Xqs on the map and in the legend.
What is the name, age, and
composition of the formation? Which of the rocks that you previously described best matches
the description for Xqs?
Quartzofeldspathic gneiss, 1,710 MA, fine grained, medium gray
Granodiorite
5)
Find the rock formation labeled PPf on the map and in the legend.
What is the name, age, and
composition of the formation? Which of the rocks that you previously described best matches
the description for PPf?
Foutain formation, upper and middle Pennsylvanian, reddish brown-purple gray
Schist
6)
Find the rock formation labeled Kn/Kns on the map and in the legend.
What is the name, age,
and composition of the formation? Which of the rocks that you previously described best
matches the description for Kns?
Smocky hill shale member, upper cretaceous, dark gray on fresh sufcae
Shale
7)
Find the rock formation labeled Kpl on the map and in the legend.
What is the name, age, and
composition of the formation? Which of the rocks that you previously described best matches
the description for Kpl?
Pierro shale, upper cretaceous, dark olive – gray shale
Shale
5
Rocks Lab 3
GEOL 121
8)
Find Horsetooth Reservoir on the map.
a.
Which formations form the east and west edges of Horsetooth Reservoir? What is their
composition?
Pierre shale and boulder creek granodiorite
Dark olive – gray shale, light to dark gray, medium gain
b.
Which formations are underneath Horsetooth Reservoir? What is their composition?
Lykins formation – siltstone that is water proof
9)
Why do you think the reservoir was placed where it was?
On siltstone because siltstone is a rock that is water proof
10)
What are one or two other potential ways that geologic maps such as this one could be
used by non-geologists to inform their decisions or planning?
To determine which land to build structures on
6
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help