Sediment and Sedimentary Rocks

1

• Sediment and Sedimentary Rocks

Big rocks into pebbles, Pebbles into sand. I
really hold a million, million Rocks here in my
hand. Florence Parry Heide
Created from the scraps of old rocks
2
Sedimentary RocksTerms

• Regolith rock and mineral fragments produced by
  weathering
• Sediment regolith that has been transported by
  wind, water or ice
• Soil portion of regolith that supports plant life

3
Sedimentary Rocks Characteristics

• Loose, solid particles
• sediments
• Unconsolidated
• Classified based on size of individual fragments

4
Four Fundamental Components of Sedimentary Rocks

1. Grains/Clasts sand, gravel or fossils
2. Matrix fine grained clay-sized sediment
3. Cement chemically precipitated mineral material
4. Porosity space with no mineral matter

Cement
Clasts, matrix and iron oxide cement (reddish
brown colour)
5
Types of Sedimentary Rocks

• 2 main types of sedimentary rocks (based on
  composition)
• Clastic
• Inorganic sediments
• rocks made up of broken and worn particles of
  rocks and minerals
• Non-Clastic
• Organic sediments
• sediment precipitates from solution in water
  originating from chemical and organic processes

Breccia
Chert from Will County, Illinois
6
Characteristics of Clastic Sediment

• Clastic sediment is divided into four main size
  classes (based on texture as well)
• Gravel
• Sand
• Silt
• Clay

Bedrock outcrop
River gravel
Beach sand
Clayey silt
Marine clay
7
Properties of Clastic Sedimentary Rock

• Processes
• Lithification / Diagenisis
• Compaction
• Pressure from recent, overlying sediment
• Cementation
• Hardening
• Stratification
• Layering

8
How Clastic Sedimentary Rock Form

• Clastic sedimentary rocks originate because of
• Weathering
• Erosion/Transportation
• Deposition/Burial
• Lithification / Diagenesis

9
Weathering

• Destroying rock

The rocks that make high ridges are much more
resistant to weathering than the surrounding
rocks
10
Erosion and Transport

• Sediments on the move

This stream carries sediment that has weathered
from nearby mountains at Polychrome Pass, Alaska
11
Deposition/Burial

• Sediments settling down

These pebbles were deposited in a stream that
once flowed over this area in Indiana, USA
thousands of years ago. Now they are part of a
clastic sedimentary rock called conglomerate