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"Profile of a dune, from back to front, showing its relation to the wind. The flow-lines of air are drawn above, with the eddy in front of the dune." -Gilbert, 1910

Dune and Wind

"Profile of a dune, from back to front, showing its relation to the wind. The flow-lines of air are…

"Diagram of the progress of a dune, from a to be. The arrow flies with the wind. A live tree standing before the dune when it is at a will be buried by the advance to b. Another tree, previously killed and still covered by the dune, will be brought to light when it has reached b." -Johnson, 1910

Dune Progress

"Diagram of the progress of a dune, from a to be. The arrow flies with the wind. A live tree standing…

Ophioglossum vulgatum, or Southern Adderstongue is a fern-like plant commonly growing in sand dunes.

Southern Adderstongue

Ophioglossum vulgatum, or Southern Adderstongue is a fern-like plant commonly growing in sand dunes.

Blowout Grass (Redfieldia flexuosa) is a grass found on sand dunes. "a, spikelet; b, flower; c, glumes." -Whitney, 1911

Blowout Grass

Blowout Grass (Redfieldia flexuosa) is a grass found on sand dunes. "a, spikelet; b, flower; c,…

A type of ripple mark in the Lop-Nor Desert in Turkestan.

Ripple Mark in Lop-Nor Desert, Turkestan

A type of ripple mark in the Lop-Nor Desert in Turkestan.

A type of ripple mark in the Lop-Nor Desert in Turkestan.

Ripple Mark in Lop-Nor Desert, Turkestan

A type of ripple mark in the Lop-Nor Desert in Turkestan.

A type of ripple mark in the Lop-Nor Desert in Turkestan.

Ripple Mark in Lop-Nor Desert, Turkestan

A type of ripple mark in the Lop-Nor Desert in Turkestan.

A type of ripple mark in the Lop-Nor Desert in Turkestan.

Ripple Mark in Lop-Nor Desert, Turkestan

A type of ripple mark in the Lop-Nor Desert in Turkestan.

Cross-section of a dune near Ostend, Belgium showing Eolian cross-bedding.

Dune with Eolian Cross-bedding

Cross-section of a dune near Ostend, Belgium showing Eolian cross-bedding.

Cross-section of a dune near Ostend, Belgium showing Eolian cross-bedding.

Dune with Eolian Cross-bedding

Cross-section of a dune near Ostend, Belgium showing Eolian cross-bedding.

In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. Each layer is generally one of a number of parallel layers that lie one upon another, laid down by natural forces. They may extend over hundreds of thousands of square kilometers of the Earth's surface. Strata are typically seen as bands of different colored or differently structured material. Individual bands may vary in thickness from a few millimeters to a kilometer or more. Each band represents a specific mode of deposition -- river silt, beach sand, coal swamp, sand dune, lava bed, etc. Eozoic strata pertains to rocks or strata older that the Paleozoic, in many of which the eozoön has been found.

Eozoic Strata

In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally…

A map drawing and drafting topography symbol illustrating sand dune.

Sand Dunes Relief or Terrain Topography Symbol

A map drawing and drafting topography symbol illustrating sand dune.

Also known as Salix cordata. The branch of a Sand Dune Willow, native to northeast North America.

Branch of Sand Dune Willow

Also known as Salix cordata. The branch of a Sand Dune Willow, native to northeast North America.