Strike and Dip
Sedimentary rock units, because they are usually deposited in horizontal layers, are most useful when studying rock deformation. If the sedimentary rock layers are horizontal, geologists infer that the area … Read More
Category: Structural geology
Principle of Cross-Cutting Relationships
Figure 1 shows layers of rock that have been offset by a fault, a fracture in rock along which displacement occurs. It is clear that the strata must be older … Read More
Anticlines and Synclines
The two most common types of folds are anticlines and synclines (Figure 1). Anticlines occur when compressional stresses squeeze sedimentary layers into arch-like folds. These upfolded structures are sometimes spectacularly … Read More
Describing and Classifying Soils
The factors controlling soil formation vary greatly from place to place and from time to time, leading to an amazing variety of soil types. These vertical differences, which usually become … Read More
The Richter and Mercalli Scales
Seismic waves are characterized by their wavelength and amplitude. Shorter-wavelength and higher-amplitude waves are the most destructive (Figure 1). Earthquakes happen all the time everywhere on Earth. Most are so … Read More
Principle of Inclusions
Sometimes inclusion can aid in the relative dating process. Inclusion is a fragment of one rock unit that have been enclosed within another. The basic principle of inclusion is logical … Read More
Translation Slides along Bedding Planes
Rockslides and other types of slides involve the displacement of material along one or more discrete shearing surfaces. The sliding can extend downward and outward along a broadly planar surface … Read More
Kinking and chevron folding
Kink bands are common in well-laminated and anisotropic rocks rich in phyllosilicate minerals, and some field occurrences are shown in Figure 1. Kink bandsare centimetre to decimeter wide zones or … Read More
Convolution
Convolute lamination or convolute bedding is a special type of intraformational deformation layering or lamination, characterized by meandering and winding laminates within a layer in concordant sequence with roof and … Read More
What Causes Rock to Deform?
Every body of rock, no matter how strong, has a point at which it will deform by bending or breaking. Deformation (de = out, forma = form) is a general … Read More