STRUCTURES

 
UNDEFORMED (?)

The horizontal rock layers that form the upper part of Grand Canyon

TILTED ROCK LAYERS:

The sedimentary layers in this large roadcut near Denver, CO. can be clearly recognized by the variation in color. These layers can be recognized as having been deformed because they have been tilted so they are dipping to the east (the left side of photo). This deformation was related to the uplift of the Rocky Mountains.

FOLDS

One of the ways rocks deform is by folding. Squeezing of these rocks have caused the once planar rock layer to buckle into a series of small folds. Note that overall vertical orientation of this presumably originally horizontal layer indicated that it either has also been tilted, or is part of a larger fold.

ANTICLINE: Anticline exposed along a road cut in the Canadian Rockies. Sedimentary layers visible in this photo have been folded. Layers on the left side of the photo are dipping to (tilted down toward) the left. Layers on the right side of the photo are dipping to the right. Note in both cases the layers dip away from the crest (high point on each layer) of the fold. This forms the concave downward shape that is common with an anticline. As long as the layers are not overturned the oldest layers should be in the core of this fold.
SYNCLINE: This fold in the Canadian Rockies is next to the anticline shown above. This syncline involves the same rock layers, but here they form a concave up fold. Note thet the layers on the left and right side of the fold dip in toward the middle. If these rock layers are not overturned the youngest rocks are in the middle of the fold.
Anticlines and synclines commonly found next to each other. This mountain side in the Canadian Rockies exposes a good example of an anticline-syncline pair.

(Note that the darker green areas on the side of the mountain are full grown trees)

Thrust Fault

Geology student points out fault runs diagonally from lower right to upper left in the outcrop.  The hanging wall of this fault is to the upper right.  The footwall is to the lower left. Note the light colored bed in the footwall that meets the fault just to the left of the student's outstretched hand.  This bed matches with  the light colored bed about a 1/2 meter above the outstretched hand in the hanging wall.  Because the bed in the hanging wall has moved up relative to the same bed in the footwall this is a thrust (or reverse) fault.

Major Thrust Fault

The White Rock thrust of the Wind River Range in Wyoming has placed older Proterozoic ages rocks on top of younger Phanerozoic strata.

 
 
Normal fault

Note the dark shale layer within these limestones.  (The shale has weathered more than the limestone in this semiarid climate so it does not outcrop as well)  If you trace the shale across the photo from left to right you will see this dark band stop, than reappear lower in the photo.  This offset of the shale is due to a fault than runs from upper left to lower right in this photo.  The hanging wall is to the right side of the fault.  The black shale layer in the hanging wall has dropped down relative to the shale in the footwall, so this is a normal fault.