Earth History - Table of Contents. RELATIVE vs. ABSOLUTE LAWS UNCONFORMITIES GEOLOGIC SECTIONS. Which graph shows the relative duration of geologic time for the Precambrian, Paleozoic, Mesozoic, and Cenozoic time intervals?. Who’s got the TIME?.
Which graph shows the relative duration of geologic time for the Precambrian, Paleozoic, Mesozoic, and Cenozoic time intervals?
“Clocks in Rocks”
"Sediments are usually deposited in horizontal layers."
He called this
a. Igneous intrusion is younger than rock it has intruded(cut across). Pre-existing rock will undergo CONTACT METAMORPHISM
b. Faults – younger than rock displaced
YOUNGEST ON TOP
OLDEST ON BOTTOM
(1) Cambrian (3) Devonian
(2) Ordovician (4) Permian
Bedrock outcrops A and B are located at two different locations along the Genesee River in western New York State. Rock layers 1, 2, and 4 are the same in both outcrops.
Which statement best explains why rock layer 3 is missing from outcrop B?
(1) A fault exists between outcrops A and B.
(2) Erosion created an unconformity between rock layers 2 and 4 in outcrop B.
(3) A volcanic eruption destroyed rock layer 3 in outcrop B.
(4) Metamorphism of outcrop A created rock layer 3.
Unconformities are usually shown in block diagrams with a wavy line to represent the buried eroded surface interface between layers
Tilted Ordovician Shales and Sandstones
Index fossils - any animal or plant that is characteristic of a particular span of geologic time or environment.
2 criteria must be met
“walking the outcrop”
LIKE AN INDEX FOSSIL
VOLCANIC ASH LAYER AT THE SAME TIME AS THE DINOSAURS BECAME EXTINCT LEAD SCIENTISTS TO LOOK FOR METEORITE CRATER Chicxulub Crater 65 mya 170 km. Wide