Geology of Urban Watersheds - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 27

Sediment
layers

FIGURE 2.4
Example of very fine horizontal layering within a clastic sedimentary deposit. Sample is approximately 8 cm
vertical by 6 cm horizontal. (Photo by Daniel T. Rogers.)

Stratigraphic
column

E

D

Sequence of
depositional
strata

C

B

A

FIGURE 2.5
Example of a stratigraphic sequence demonstrating the principle
of superposition.

and wind can also significantly erode or rework a layer of sediment after it has been
deposited.

2. The principle of superposition defines the depositional sequence in undeformed
strata of rock or sediment. Strata are sheets or individual layers of sedimentary
deposits, and as a group, are visibly distinct from those above and below. Figure 2.5