Lecture 19 Flashcards
(32 cards)
Who created the map that changed the whole world?
Sir William Smith-first geological map realized on a whole country.
How did Sir William Smith create his map?
Noted that limestone layers are younger versus older. Combined rock record with fossils in these rocks. Fossils have stratigraphical layers.
What are index fossils?
Fossils that can be used for dating the layers. Could be correlated with other stratigraphical layer
What is the Principle of Biological Succession (Sir William)
Once something goes extinct, it does not live again. Fossil record in Earth’s history is not repeatable, gradual change from oldest fossil till current
What did William Smith regard the fossil record as?
A sign of continuous divine creation (last creationist to have a say in science).
What was the main question that formed the principle of inclusion? (Charles Lyle)
Worked with primarily sedimentary rocks. Wondered if we can include metamorphic and igneous rocks in the same way?
What is the principle of inclusion?
Inclusion (rock inside of another rock), is older than the one it’s embedded in. Older rock is situated both above and below. Cannot apply principle of superposition.
What is the Principle of Cross cutting relations (igneous rocks)
Dikes that cut through rocks are younger than the one that they cut through
What are the relative ages of lava flows?
Lava flow cooks the preexisting rocks. Flow is younger than both the rocks below and above. Cooked rock between sedimentary rocks is younger than both above and below. Igneous rocks are injected between sedimentary rocks (Sill)
What are the 4 eons that earth is divided in (in stratigraphical order).
Hadean, Archean, Proterozoic, Phanerozoic.
What was the Hadean Eon?
Earth is a globe of molten matter (no rock record). Can correlate with Solar Nebula Theory
What was the Archean Eon?
Contains the oldest rocks we know, from the North West Territories and Quebec
What is the Proterozoic Eon?
Includes rocks with earliest life forms (even though life appeared in the Archean). Onsent of plate tectonics. Movement went from vertical to horizontal. Change was gradual. Mostly small sized, single celled organisms (microbes)
What is the Phanerozoic era?
Vast number of large sized fossils, no microbes.
When did the Cambrian Explosion happen?
In the boundary between the proterozoic and phanerozoic
What was the Cambrian Explosion?
Organisms in oceans began to dig in sediments. New food sources created complex body forms. Nutrients in oceans increased, large organisms evolved. No predators existed yet. Lots of skeletons.
Why is it hard to separate Archean and Proterozoic rocks?
Often affected by metamorphism.
What is the Super Eon Level?
Precambrian groups. Rocks are “full body texture”
What are the 3 subdivisions of the Phanerozoic?
Eras: Paleozoic, Mezozoic, Cenozoic
What is the Paleozoic?
Life forms with little resemblance to modern life forms
What is the Mezozoic?
Life forms with resemblance to modern ones (ex: Conifers, Angeospore evolution, continental floras almost the same as today.
What is the Cenozoic?
Life forms with strong resemblance to those today.
What was the lower paleozoic boundary?
When the Cambrian Explosion happened
When did the most severe change to Earth happen?
In between the palaeozoic and Mesozoic
