|theImage.com     Notes on Basic Geology|
|Notes created & information organization based on the book:
"The Dynamic Earth - an introduction to physical geology"
Brian Skinner & Stephen C. Porter   (further book information here)
also look at www.wiley.com for additional resource information
|Deformation - Page 4|
|Energy Requirements||From the earth's interior heat.|
What forces are used?
|Tectonic forces are used to deform the crust.|
|Three kinds of stress|
|Brittle and Ductile|
Brittle deformation: chalk, glass, (Will break more often than bend)
Ductile Deformation: copper, butter, rubber, (Will bend more before breaking)
Things that promote Ductile Bending:
1.) heat (plastic, glass, etc. etc.)
|CRUST||All brittle - down to about 15 km - (based on quartz content)|
|Lithosphere||Some brittle down to about 40 km then lessens|
|-------BOUNDARY ------||By definition the boundary between the aesthenosphere. and lithosphere is where there is NO brittle character left to the rocks. Rocks are all ductile until we get down to the Mesosphere.|
|Fault & Joint|
|A joint is a fracture in a rock that shows no movement. A fault is a fracture which shows movement.|
|Dip and Strike||
When the underlying rock is no longer in a horizontal pattern, it can still be mapped. The two defined directions are called dip and strike.
The strike is the direction which the inclined sediment crosses ground level. It can sometimes be determined by mapping many rock out croppings and then aligning them until the direction can be ascertained.
The dip is the angle of incline of the raised beds into the earth. It is measured from the horizontal down to the dipping plane.
|Hanging wall and footwall|
The hanging wall is the wall that is located above the fault line. The lower block is called the footwall. It makes no difference which way the rocks move only their relative location.
Normal fault: hanging wall drops (down direction)
Reverse fault: hanging wall rises (up direction)
Strike fault: walls move like transverse plates
Oblique fault: like the movie - two directions.
Hinge fault: fault becomes wider at one end