may be separated by stone lines. Size-sorted, rounded, 

 or subrounded pebbles or cobbles, and burnished peds 

 contrast with unsorted colluvial deposits. HP 



Sloughed till— Water-saturated till that has flowed slowly 

 downhill from its original place of deposit by glacial 

 ice. It may rest on other till, on glacial outwash, or on a 

 glaciolacustrine deposit. NTC 



Slump— The downward slipping of a mass of rock or 

 unconsolidated material of any size, moving as a unit 

 or as several subsidiary units, usually with backward 

 rotation on a more or less horizontal axis parallel to the 

 cliff or slope from which it descends. HP 



Solifluction — Slow viscous downslope flow of water 

 saturated regolith; especially the mass-wasting process 

 occurring in areas of frozen ground, with alternate 

 freezing and thawing of surficial materials, (fig. B-9) HP 



Spit — (a) A small point or low tongue or narrow embank- 

 ment of land, commonly consisting of sand or gravel 

 deposited by longshore drifting and having one end at- 

 tached to the mainland and the other terminating in 

 open water, usually the sea; a fingerlike extension of 

 the beach, (b) A relatively long, narrow shoal or reef 

 extending from the shore into a body of water. GG 



Spur — A secondary divide between minor drainage systems 

 of an area, that generally has an inverted "V" shape, 

 and occurs considerably below the elevation of the 

 associated ridge. HP 



Steptoe — An island-like area in a lava flow. HP 



Stone line — A sheet-like concentration of coarse frag- 

 ments in surficial deposits. In cross-section, the line 

 may be marked only by scattered fragments or it may 

 be a discrete layer of fragments. The fragments are 

 more often pebbles or cobbles than stones. A stone line 

 generally overlies material that was subjected to weath- 

 ering, soil formation, and erosion before deposition of 

 the overlying material. Many stone lines seem to be 

 buried erosion pavements, originally "formed by run- 

 ning water on the land surface and concurrently cov- 

 ered by surficial sediment" (Ruhe 1975). HP 



Strath terrace — (See stream terrace.) HP 



Stratified — Arranged in strata, or layers. The term refers 

 to geologic material. Layers in soils that result from the 

 processes of soil formation are called horizons; those 

 inherited from the parent material are called strata. HP 



Stream terrace — One of a series of platforms in a stream 

 valley, flanking and more or less parallel to the stream 

 channel, originally formed near the level of the stream, 

 and representing the dissected remnants of an aban- 

 doned flood plain, stream bed, or valley floor produced 

 during a former stage of erosion or deposition. Ero- 



sional surfaces cut on bedrock and thinly mantled with 

 stream deposits (alluvium) are designated "strath ter- 

 races." Remnants of constructional valley floors are 

 termed "alluvial terraces." (See terrace.) HP 



Structural bench (or bench) — A platform-type, nearly 

 level to gently inclined erosional surface developed on 

 resistant strata in areas where valleys are cut in alter- 

 nating strong and weak layers with an essentially hori- 

 zontal attitude. Structural benches, in contrast to stream 

 terraces, have no geomorphic implication of former, 

 partial erosion cycles and base-level controls, nor do 

 they represent a stage of flood-plain development fol- 

 lowing an episode of valley trenching. HP 



Summit — A general term for the top, or highest level of 

 an upland feature such as a hill, mountain, or table- 

 land. It usually refers to a high interfluve area of lower 

 slope that is flanked by steeper hillslopes, (for example, 

 mountain fronts, or tableland escarpments). Summit 

 areas may or may not include distinct crest lines or high 

 points that rise above their general level, (fig. B-2) HP 



Swale — (a) A slight depression, sometimes swampy, in 

 the midst of generally level land, (b) A shallow depres- 

 sion in an undulating ground moraine due to uneven 

 glacial deposition, (c) A long, narrow, generally shal- 

 low, trough-like depression between two beach ridges, 

 and aligned roughly parallel to the coastline. GG 



Swash zone — The sloping part of the beach that is alter- 

 nately covered and uncovered by the uprush of waves, 

 and where longshore movement of water occurs in a 

 zigzag (upslope-downslope) manner. GG 



Swamp — An area intermittently or permanently covered 

 with water, having shrubs and trees but essentially 

 without the accumulation of peat. GG 



Swell-and-Swale topography — Topography of ground 

 moraine having low relief, gentle slopes, and well 

 rounded hills or hummocks interspersed with shallow 

 depressions. HP 



Syncline— A unit of folded strata that is concave upward. 

 In a simple syncline, beds forming the opposing limbs 

 of the fold dip toward its axial plane. (See anticline and 

 monocline.) HP 



Tableland— A general term for a broad upland mass with 

 nearly level or undulating summit area of large extent 

 and steep sideslopes descending to surrounding low- 

 lands. Varieties include plateaus and mesas. HP 



Talus— Rock fragments of any size or shape (usually 

 coarse and angular) derived from and lying at the base 

 of a cliff or very steep, rock slope. The accumulated 

 mass of such loose broken rock formed chiefly by fall- 



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