EPS SCI 15 Lecture Notes - Lecture 3: Baraboo Range, Mudcrack, Stegosaurus
29 Apr 2018
School
Department
Course
Professor
Lec 3: Geology
April 10
TIME SCALE
●T. rex and Stegosaurus did not exist during the same time period, but rather existed 84
million years apart from one another
○ Stegosaurus
(≈150 million years ago) → Jurassic
○ Tyrannosaurus
(≈66 million years ago) → Cretaceous
OUTLINE
● Question: Is the Earth's history dominated by “time’s arrow” or “time’s cycle”?
● Clarify the laws of geology
● Distinguish relative from absolute time
● Explain plate tectonics & continental drift
CONCEPTIONS OF EARTH’S HISTORY
●catastrophism (“time’s arrow”)
: assumption that Earth’s history was dominated by
violent events
○ 19th century geology → dominated by Christian theology
■ Georges Cuvier
(paleontologist) - the biblical flood was thought to be the
primary driver of Earth’s formations
○ Eschatology As a Driver of Time’s Arrow: → Examples
:
■ Resurrection of the Dead (Syria)
■ Ripple Marks (Bay Beach) → evidence of shallow bodies of water
■ Fossil Ripple Marks (Baraboo Range)
■ Modern Mud Cracks vs. Fossil Mud Cracks (Virginia)
● uniformitarianism (“time’s cycle”)
: we can use cause & effect to determine causes of
past events
○ Charles Lyell
- believed that patterns occurred repeatedly to form Earth’s
formations
STRATIGRAPHY
● different regions of the world are covered in different types of rocks → looked at
stratigraphic maps (discovery of relative ages
)
●rock cycle
: shows the cyclical nature of rocks
● sedimentary rocks → heated due to high heat & pressure over time → become
metamorphic rocks → become liquid → can either:
○ come out through volcanos
○ cool through and go back towards land → igneous rocks
● erosion results in sedimentary rocks (dinosaur bones found here)
LAWS OF RELATIVE AGE
● principle of superposition
: in a sedimentary sequence that has not been overturned,
the oldest rock units are always at the bottom
● principle of lateral continuity
: most sedimentary rock units were originally deposited
over a large area, but later became isolated by erosion or faulting
● principle of original horizontality
: sedimentary layers are originally deposited lying flat
(ie. parallel) to the Earth’s surface
● principle of cross-cutting relationships
: if one rock cuts across another, it is younger
● rule of inclusions
: if a unit contains a clast, or inclusion of another rock unit → the clast
or inclusion is older
Document Summary
T. rex and stegosaurus did not exist during the same time period, but rather existed 84 million years apart from one another. Stegosaurus ( 150 million years ago) jurassic. Tyrannosaurus ( 66 million years ago) cretaceous. Catastrophism ( time"s arrow ) : assumption that earth"s history was dominated by violent events. 19th century geology dominated by christian theology. Georges cuvier (paleontologist) - the biblical flood was thought to be the primary driver of earth"s formations. Eschatology as a driver of time"s arrow: examples : Ripple marks (bay beach) evidence of shallow bodies of water. Modern mud cracks vs. fossil mud cracks (virginia) Uniformitarianism ( time"s cycle ) : we can use cause & effect to determine causes of. Charles lyell - believed that patterns occurred repeatedly to form earth"s past events formations. Different regions of the world are covered in different types of rocks looked at stratigraphic maps (discovery of relative ages )
