 But these beds are of no use in correlation and should not be taken as a "high resolution" tool for stratigraphy without a severe biostratigraphic control.Seasonal changes in weather can create cyclic sediments in the form of alternating bands of clay and silt (also known as varves).For example, in a glacial region where sediments are deposited in a lake, coarse sediments that are trapped in ice are released when the ice melts in the summer.