1. Geologic Profiles
The Earth can tells us its history if we only look at the clues
Types of rocks present
Ages
Formations present
Sills
Dikes
Faults

2. Igneous Intrusive rocks
Form as magma solidifies underground
Batholith
Dike
Sill
Pipe or Neck
Laccolith or Lopolith
Phacolith: anticline or syncline

3. a sill is a tabular pluton that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock.
the sill does not cut across preexisting rocks, in contrast to dikes, which do cut across older rocks.

4. Dikes
A dike or dyke in geology is a type of referring to any geologic body that cuts discordantly across
be either intrusive or sedimentary in origin.

5. Volcanic Necks Volcanic neck Igneous intrusion
How did Devil’s tower form?

6. Batholith
is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust.
Batholiths are almost always made mostly of felsic or intermediate rock-types, such as granite, quartz monzonite, or diorite (see also granite dome).

8. Determining Age Two Methods 1. Relative Age 2. Absolute Age

9. Relative Age: How old is a rock in comparison to others
Examine geologic profiles
Examine fossils present in the rock
Index fossil: a fossil of a plant or animal that was very common during a specific time period
(Who’s on First Activity)
Law of Superposition
_________________
A B A A
B A A B
A A C A
A B B A B

11. Absolute Age: determining approximate age of rock
Radioactive Dating: can be used on igneous rocks and certain fossils
radioactive isotopes are present when rocks are made and living things die
Radioactive isotopes decay over time and we can measure the amount left to determine age
Short clip on C14

12. Works Cited
"Copyright 2009 by Andrew Alden, geology.about.com, reproduced under educational fair use.“
Wikipedia