What are periclinal and anticlinal divisions?
These are both geological terms. A pericline is a geological feature whereby the Earth's crust is folded either upward or downward in a regularly shaped contour pattern that gradually recedes to flat as you move outwards. The two major types of periclines are anticlines and synclines.
An anticline is a convex fold in the Earth's crust. Convex means that it bends upward from the surface of the crust and appears to be an upside down "U" shape. Anticline divisions produce upward thrusted dome shaped protrusions that tend to erode over time. As a result, the oldest layer of the rock strata is at the center of the anticline while the youngest layers of the rock strata are on the outer edges of the anticline.
A syncline is the opposite of an anticline. It is concave, or U shaped, and forms a basin type structure that erodes at the edges. The oldest strata are at the ends and the youngest strata are at the center.