APPENDIX B 



Alluvium. Sediments deposited by rivers and streams which overflow their 

 banks. The area in which alluvium is deposited by streams is the flood 

 plain. 



Basalt. A dense, hard, dark-colored rock formed from lava flows. 



Bedrock. The solid rock londerlying soils and geologic materials at depths 

 ranging from zero (where exposed) to several hundred feet. 



Consistence. The combination of properties of soil material that determines 

 resistence to crushing and its ability to be molded or changed in shape. 

 Consistency depends mainly on the forces of attraction between soil particles. 

 Terms commonly used to describe consistency are as follows: 



Firm. When moist, crushes under moderate pressure between thumb 

 and forefinger, but resistance is distinctly noticeable. 



Friable. When moist, crushes easily under moderate pressure 

 between thumb and forefinger, and coheres when pressed together. 



Loose. Noncoherent, crumbles under very slight pressure. 



Crystalline rock. A general term used for rocks composed of crystals or parts 

 of crystals. 



Deposit. Material left in a new position by a natural transporting agent such 

 as water, wind, ice, or gravity or by the activity of man. 



Esker (geological). A narrow ridge or mound of gravelly and sandy drift 

 deposited by a small glacial stream. 



Flood plain. The land bordering a stream, consisting of sediments from 

 overflow of the stream and subject to inundation when the stream is at flood 

 stage. 



Fragipan (hardpan). Compact layer of soil rich in silt and sand, and low in 

 clay. The fragipan commonly interferes with water and root penetrations. 

 I^en dry, the material appears to be cemented, but when moist, it is brittle 

 and breaks suddenly under pressure. 



Glacial drift. Earth and rock materials picked up, mixed, crushed, 

 transported, and deposited by glacial ice or by water melted from the glacial 

 ice. 



B-1 



