TITLE     INTRODUCTION     DETRITAL ROCKS     CHEMICAL ROCKS     

BIOCHEMICAL ROCKS     ENVIRONMENTAL CLUES     CREDITS   

GRADED BEDDING       

cross bedding       ripples       mud cracks   

raindrop impressions       bioturbation      tracks and  trails      fossils    

A graded bed forms as a current of water (stream or ocean) transporting a variety of sediment grains slows gradually.   Larger sediment grains will settle first, followed by smaller grains as the current's energy decreases.   So, a typical graded bed has larger grains at the bottom, with progressively smaller grains toward the top.   Graded beds are characteristic of stream deposits, but they can also form where turbulent ocean currents move rapidly from the continental shelf or continental slope out into deeper water.

          A single graded bed (note ID card for scale).            A series of graded beds, with Scott for scale.

Return to the top of this page.