Graded Bedding

Imbrication

In strong current flows, elongate and discoidal pebbles can become oriented with an upstream dip.

Gravity Flow Bedforms

Gravity-flow bedforms are those that are produced by a down-slope movement of water-saturated sediment under the driving force of gravity.

Turbidites

Photo by W. W. Little

Surface Markings

Surface markings form on the tops of beds following episodes of deposition and are most common on subaerially exposed surfaces.

Parting Lineations

Photo by W. W. Little

Dessication Cracks

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Rain Imprints

Photo by W. W. Little

Sole Marks

Photo by W. W. Little

Flute Casts

Photo by W. W. Little

Tool Marks

Saltation Marks

Roll Marks

Soft-sediment Deformation

Soft-sediment deformation is considered by many to be an early stage of diagenesis and includes features formed by mostly by slumping and compaction.

Photo by W. W. Little

Distorted (Contorted) Bedding

Distorted (or contorted) bedding is the result of slumping or shaking in saturated sediment.

Flame Structues

Photo by W. W. Little

Photo by W. W. Little

Load Structures

Compaction due to vertical accumulation of sediment can lead to the deformation of underlying beds.

Ball-and-Pillow Structures

Extreme density contrasts between sedimentary beds can lead to the development of diapirs, as the lower density material rises through those of a higher density.

Sedimentary Diapirs

Photo by W. W. Little

Water-escape Structures

Compaction due to vertical accumulation of sediment can lead to the forced expulsion of fluids and resulting deformational structures.

Photo by W. W. Little

Primary Biological Structures

Photo by W. W. Little

Algal Structures

Photo by W. W. Little

Photo by W. W. Little

Stromatolites

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Thrombolites

Trace (ichno-) Fossils

Trace fossils consist of burrows (escape, shelter), tracks, trails (locomotion, feeding), and other features moving through or across previously deposited sediment. These features are given Linnean names and are extremely useful for determining depositional environment.

Photo by W. W. Little

Burrows

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Bioturbation

Bioturbation is the disturbance and mixing of sediment by biological activity and may completely eliminate older physical structures.

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Tracks and Trails

Photo by W. W. Little

Photo by W. W. Little

Photo by W. W. Little

Diagenetic Structres

Photo by W. W. Little

Concretions

Photo by W. W. Little

Photo by W. W. Little

Dissolution Cavities

Photo by W. W. Little

Solution Breccia

Photo by W. W. Little

Unconformities

Photo by W. W. Little

Intraformational Unconformities

Photo by W. W. Little

Photo by W. W. Little

Diastems

Paleocurrent Indicators

Many sedimentary structures, particularly those produced by unidirectional currents, retain characteristics that can be used to determine paleoflow direction.

Cross-beddingLateral accretion surfacesChannel formsRipple morphologyImbricationFlute castsTool marks

http://walrus.wr.usgs.gov/seds/bedforms

Videos on Sedimentary Structures

http://geofaculty.uwyo.edu/heller/sed_video_downloads.htm

http://walrus.wr.usgs.gov/seds/bedforms/pindex.html