Types of folds
During mountain building or compressional stress, rocks may deform
plastically to produce folds. Generally, a series of folds is
produced, much as a carpet might wrinkle when you push on one end.
The up-folds and the down-folds are adjacent to one another, and
grade into one another.
Basic types of folds: 1. anticlines - upfolds 2. synclines -
downfolds
Classification of Folds
Folds can be classified based on their appearance.
- If the two limbs of the fold dip away from the axis with the
same angle, the fold is said to be a symmetrical
fold.
- If the limbs dip at different angles, the folds are said to be
asymmetrical folds.
- If the compressional stresses that cause the folding are
intense, the fold can close up and have limbs that are parallel to
each other. Such a fold is called an isoclinal fold
(iso means same, and cline means angle, so isoclinal means the
limbs have the same angle).
- If the folding is so intense that the strata on one limb of the
fold becomes nearly upside down, the fold is called an
overturned fold.
- An overturned fold with an axial plane that is nearly
horizontal is called a recumbant fold.
- A fold that has no curvature in its hinge and straight-sided
limbs that form a zigzag pattern is called a chevron
fold.
Clastic sedimentary rocks.
Fold: Picture and Identify
Earthcache Requirements:
1.) Picture requirement:
My intentions are to have you post your picture with the fold in
the background. If you refuse to post your face in the picture,
then each log must have a unique picture for each log. Tilting the
picture with a photo program will not be acceptable for unique.
Group photos must reference who's picture you are in otherwise. A
unique picture must be included with every log if you are not in
the picture. .
Email me the following answers...
2. Describe the types of folds that you see.
3. What type of rock(s) make up this formation?
4. Tell me something about the area; geologic related that you
found interesting. (Unique answers for each person in group
finds)
Please do not post answers in your posts.
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