This true dip direction is always perpendicular (i.e., at a 90 degree angle) to strike. If a marble is held anywhere along the strike line on a layer or planar feature and then is released, thus allowing it to roll down the layer or planar feature, the marble would roll along a line showing true dip direction. Dip direction is the compass direction (bearing) of maximum inclination of the layer or planar feature down from the horizontal. Then, and only then, is a strike direction written that is not relative to north.ĭip, as a part of the measurement of the attitude of a layer or planar feature, has two components: dip direction and dip magnitude. The only exception to this north rule occurs where strike is exactly east-west. A typical bearing is given, for example, as N 45 ° E, which is a shorthand notation for a bearing that is 45 degrees east of north (or half way between due north and due east). According to convention, the compass direction (or bearing) of this line is always measured and referred to relative to north. The intersection of two flat planes is a straight line, and in this instance, the line is geologic strike. Strike is defined as the compass direction, relative to north, of the line formed by the intersection of a rock layer or other planar feature with an imaginary horizontal plane.

The method involves measurement of strike and dip of the rock layers or planar features.

Geologists use a prescribed method of determining the attitude (or orientation in three-dimensional space ) of rock layers or any other planar geological feature (e.g., metamorphic foliation, fractures, faults, and tops of tabular units like formations).

Dip dip direction examples compass