______________________________________________________________________________ ______________________________________________________________________________ -There are several different types of fold structures: a) Anticline -An upward fold. In cross section it resembles the and on a geologic map it looks like letter “A” parallel lines. -Oldest strata are found in the middle of the fold. b) Syncline -A downward fold. In cross section it resembles the letter and on a geologic map it looks “U” like parallel lines. -Youngest strata are found in the middle of the fold. *Note: In the above diagrams you can see that strata are bent around an axis (found at the middle of the curve). This is the Fold Axis (lies within the Axial Plane). c) Plunging Anticlines -The Fold Axis does not have to be horizontal, but can at one end into the ground. “plunge” -On a map looks like a series of wavy lines or the letter The point of the the “V”. “V” indicates direction of the plunge. -Oldest strata are found in the middle of the fold. -Plunge: Angle between the fold axis and the horizontal -Trend: Compass direction of the plunge (the direction it is inclined downwards). d) Plunging Syncline -On a map looks like a series of wavy lines or the letter The open end of the “V”. “V” indicates the direction of the plunge.
______________________________________________________________________________ ______________________________________________________________________________ -There are several different types of fold structures: a) Anticline -An upward fold. In cross section it resembles the letter “A” and on a geologic map it looks like parallel lines. -Oldest strata are found in the middle of the fold. b) Syncline -A downward fold. In cross section it resembles the letter “U” and on a geologic map it looks like parallel lines. -Youngest strata are found in the middle of the fold. *Note: In the above diagrams you can see that strata are bent around an axis (found at the middle of the curve). This is the Fold Axis (lies within the Axial Plane). c) Plunging Anticlines -The Fold Axis does not have to be horizontal, but can “plunge” at one end into the ground. -On a map looks like a series of wavy lines or the letter “V”. The point of the “V” indicates the direction of the plunge. -Oldest strata are found in the middle of the fold. -Plunge: Angle between the fold axis and the horizontal -Trend: Compass direction of the plunge (the direction it is inclined downwards). d) Plunging Syncline -On a map looks like a series of wavy lines or the letter “V”. The open end of the “V” indicates the direction of the plunge.
structural_geology_student_2014.docx