Relative DatingSuperposition
Original Horizontality
Faulting
Tilting/Folding
Intrusions
Unconformities
Geologic Columns
Rock Puzzles
I. RELATIVE DATING: Determining whether an object or an event is older or younger than other objects or events.
Relative Age?
• Layer 1
• Layer 2
• Layer 3
• Layer 4
II. SUPERPOSITION: Younger rock lie above older rock.
List the rocks in order from youngest to
oldest!
A. Law of Original Horizontality – Sedimentary rocks form layers of horizontal strata.
III. Disturbed Rock Layers: Events are younger than the rock layers
A. Faulting – a break in the Earth’s curst where one rock layers will slide
B. Intrusions – when molten rock squeezes into existing rock and cools
C. Folding & Tilting – When internal forces bend or tilt rock layers
D. Unconformities – a surface that represents an area where there is a missing piece of geologic rock
FaultingCross CuttingFolding
Unconformity
Faulting
Intrusions
IV. Geochronology - the science of dating and determining the time sequence of events in the history of the Earth.
IV. Geochronology - Key
V. GEOLOGIC COLUMNS
An ideal sequence of rock layers that
contain all fossils and rock formations on Earth arranged
from oldest to youngest.
MICHIGANS GEOLOGIC COLUMN: How did geologist get this information?
MICHIGAN BASIN
• Originally shaped like a bowl
• Great sea covered MI during Paleozoic Era
• Layers formed from 24 – 30 retreats and transgressions of water or oceans
• Information taken from core samples
http://www.geo.msu.edu/geo333/MIbasin.html