Physical Geology (Lab 11: Stream Drainage Patterns)

Annular Stream Drainage Pattern

In this stream drainage pattern, a set of incomplete, concentric (round) rings of streams are connected by short radial channels. This pattern develops on eroding structural domes and folds that contain alternating folded layers of resistant and nonresistant rock types.

Centripetal Stream Drainage Pattern

In this stream drainage pattern, channels converge on a central point, often a lake or a playa (dry lake bed), at the center of a closed basin.

Radial Stream Drainage Pattern

In this stream drainage pattern, channels flow outwards from a central area, resembling the spokes of a wheel. Water drains from the inside of the pattern, where the "spokes" nearly meet, to the outside of the pattern. This pattern develops on conical hills such as volcanoes and some structural domes.

Rectangular Stream Drainage Pattern

This stream drainage pattern is a network of channels with right-angle bends that form a pattern of interconnected rectangles and squares. This patten often develops over rocks that are fractured/faulted in two main directions. The streams erode channels along the perpendicular fractures/faults.

Deranged Stream Drainage Pattern

This stream drainage pattern is a random pattern of stream channels that seem to have no relationship to underlying rock types or geologic structures.

Trellis Stream Drainage Pattern

This stream drainage pattern resembles a vine or climbing rose bush on a trellis. The main stream is long and intersected at nearly right angles by its tributaries. This pattern commonly develops where alternating layers of resistant and nonresistant layers have been tilted and eroded to form a series of parallel ridges and valleys.

Dendritic Stream Drainage Pattern

This stream drainage pattern resembles the branching of a tree. Water flow is from the branch-like tributaries TO the trunk-like main stream or river. Common where a stream cuts into flat lying layers of rock/sediment or where a stream cuts into homogeneous/crystalline igneous rock or sediment/sand.