Name: ________Key - Stover_____________________
Date: __________________
Study Guide for Investigation Exam 4 & 5 (Formation of Sedimentary Rocks)
Sediments- Particles of earth material that settle out of water___
Weathering - The natural breakdown of solid rock into smaller pieces through chemical (acids), physical,
and plant/animal action_
Erosion- _ the removal and transportation of loose earth material
Deposition- _ the settling out of eroded earth material
Matrix- _ The material that glues sand together in sandstone
Basins- _ areas of relative low elevation where water and sediments collect
_______________________________________________________________________________________
Compaction- _ the process by which the pressure on buried solid material causes the material to stick
together and change to rock
Principle of Original Horizontality- Layers of sediment are generally deposited in a flat and horizontal
position__________________________________________________________________________________
Uniformitarianism- The present is the key to the past. The way things happen today is the way things
happened in the past
Principle of Superposition- basic law, stating that in any undisturbed sequence of rock layers, the
youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and
older than the one above it
Concepts
1. Sandstone and shale are sedimentary rocks. Sandstone is made of __sand___ and a __matrix_______
and shale is made of __clay & siit________ (think about the stream table, what is left at the end?)
2. Sediments form through the processes of chemical and physical ______weathering______.
3. _Erosion_________ is the wearing away of soil and rock by weathering, mass movement, and action of
streams, glaciers, waves and wind.
4. Eroded sediments can be _____transported_______ by water, wind or ice and deposited in new locations.
5. Sediments that settle in water form a flat, ___horizontal_ layer; each layer of sediment is distinct.
6. Sediments turn into rock through the process of ______lithification_____, which involves cementation and
compaction.
7. The present is the key to the____past_____; geological processes that we observe today most likely
______occurred________ in the same way throughout Earth’s history.
8. How is sandstone formed? Explain the process.
Sandstone requires sand particles and a matrix to form. The sand sediments are buried deep under the
surface where they begin to compact. Rainwater with a matrix in it seeps into the material as the
sediments continue to compact. The water evaporates, leaving the matrix behind. The matrix cements the
sediments together, thereby forming sandstone.
9. In what environment(s) does sandstone form? How do you know?
Sandstone forms in an environment with lots of sand such as beaches or dunes. Sandstone is made out of
sand so you may infer that it would form in a place with lots of it.
10. How is shale formed? Explain the process.
Shale is made out of silt and clay in an area with slow moving water. These sediments get buried deeply by
other sediments and become compacted. The pressure squeezing the sediments is so great that all of the
water around them gets squeezed out, leaving only the sediment behind. The sediment is so compacted
that it remains together as a rock.
11. In what environment(s) does shale form? How do you know?
Shale forms in an environment with slow moving or steady water. We know because shale contains silt
and clay, and those sediments will only deposit in such places. Examples are swamps, marshes, ponds, or
lakes.
12. Why are fern plant fossils commonly found in shale?
Shale forms in swampy or marshy areas. Areas with lots of water such as these will also have lots of
plants. When some of these plants die, they fall into the sediments and get buried. Once buried, they
become fossilized within that rock
13. Sedimentary Rock Characteristics:
Rock
Texture
Rough
Color
Tan to brown, color
varies
Acid Test
No fizz
Other Observations
Crossbedding
Smooth
Dark grey, black
No fizz
Plant fossil evidence
Rough
Lighter colors –
grey, white, etc.
Fizz
Shells, corals
Sandstone
Shale
Limestone
14. Sedimentary Rock Formation Environments:
Rock
Environment
Desert OR Beach
Sandstone
Swamp/Marsh
Pond/Lake
Shale
Ocean
Evidence
Crossbedding, trace fossils of reptiles (tracks, etc.),
Dune sand particles are well sorted and show wind frosting,
beach particles have rounded edges and may look polished
Fern/leaf fossils, insect fossils possible but not as common,
clay/silt particles
Calcite, shell fossils, coral fossils, fish fossils, etc.
Limestone
15. Explain the Principle of Superposition and how it relates to rock layers.
The principle of superposition states that rock layers on the bottom of a rock column are older than the
rock layers on top. Thus, the layers get younger the further up a column you go.
16. Why does limestone fizz when hydrochloric acid is placed on it?
a. What mineral is present that reacts with the HCl acid?
Calcite (a form of calcium carbonate)
b. Explain the chemical reaction that occurs to casue the fizzing
The HCl reacts with the calcite to create carbon dioxide bubbles (the fizzing)
17. Describe the two ways that limestone can form in an ocean environment.
a. Animals create shells made of calcite (shells pieces become part of sediments)
b. The carbon dioxide (CO2) exhaled by organisms reacts with calcium in the water (direct
precipitation from ocean water).
Note: The calcium carbonate acts as a matrix and forms a layer at the bottom of the ocean.
• Over time through compaction the layer turns into limestone.
18. What is a fossil?
•
•
A fossil is any remains, trace, or imprint of a plant or animal that has been preserved in the earth’s crust
since some past geological or prehistoric time.
Any evidence of past life
In what type of rock are fossils usually found?

Sedimentary: Shale or Limestone
*** Review ALL notes and readings posted. Also review Stream Table Observation sheet