This landform group is slightly to moderately dissected by streams with the dominant stream patterns 

 being sub-parallel and parallel. Streams in this map unit are typically ephemeral at the highest 

 elevations and perennial at lower elevations. These streams are typically classified as A or Aa+ stream 

 types with gradients from 4 to 10+%. They are characterized by straight (non sinuous) cascading 

 reaches, with frequently spaced pools. When they are flowing through bedrock and boulders (A1 and 

 A2) they are very stable with low sensitivity to increases in water yields, peak flows or sediment. Some 

 of the stream reaches flow through finer materials - cobbles, gravels, or sands (A3 or A4); which can 

 yield significant sediment if disturbed. 



The riparian vegetation is dominantly Abies lasiocarpa/Streptopus amplexifolius is the riparian habitat 

 type occurring on somewhat pooriy drained sites. Abies lasiocarpa/Oplopanax horridum is the 

 dominant habitat type occurring in small pockets of pooriy drained soils. 



The nitrogen yield is moderate and the phosphorus yield is high from the portion of this landfomn group 

 having deep soils. A common situation on the rocky portions of these landforms is to have little or no 

 soil. On these sites the low erosion rates result in low phosphorus yields, and the nitrogen yields are 

 low because there is little nitrogen on these sites. Sensitive soils occur on dissected breaklands that 

 receive more than 50 inches of precipitation per year. 



Steep Alpine Glaciated Lands - (31,312 acres, 53.5% of Big Creek) 



Steep alpine glaciated lands occur in upland and alpine landscape settings and are primarily composed 

 of glacial troughwall, cirque headwall, and cirque basin landfonns. Parent materials are alpine glacial 

 debris and colluvium derived from and underiain by argillite, siltite, quartzite, limestone, and dolomite 

 bedrocks. These landforms are typically in high elevation and high precipitation areas. The vegetation 

 is a mosaic of coniferous forest, alpine meadows, and shrubland associated with avalanche chutes. 



Glacial troughwalls are formed in glacial tills on the lower elevation slopes with volcanic ash influenced 

 colluvium on the higher elevation slopes. Slope gradients range from 50 to 90 percent. Soils on the 

 lower slopes of this landform are moderately shallow to deep, are moderate to highly developed, and 

 have cobbly medium textures. 



Cirque headwalls and cirque basins are formed in glacial till on the lower elevation slopes and volcanic 

 ash influenced colluvium on the higher elevation slopes. Slope gradients range from 5 to 90 percent. 

 Soils on these landfonns are shallow to moderately deep and weakly developed with very gravelly 

 medium textures. 



The troughwall landfonns are moderately to highly dissected by streams with the dominate stream 

 pattem being parallel. Streams on this landform are usually either 1st or 2nd order, typically being 

 intermittent or ephermal at the higher elevations and perennial at the lower elevations. They are 

 characterized by moderate to high entrenchment, moderate to high confinement, and low sinuosity. 

 These streams are typically classified as Aa+ or A stream types with gradients from 4 to 10+ percent. 

 The streams are characterized by straight (non sinuous) cascading reaches, with frequently spaced 

 pools. When they are flowing through bedrock and boulders (A1/Aa+1 and A2/Aa+2) that are normally 

 very stable. However, large flows produced from either rain on snow events, or large spring runoffs 

 following wildfire events, would periodically erode these steep channels. This erosion produces fine 

 sediments that are deposited in the lower gradient stream channels. 



The cirque basin landform can have flatter gradient streams flowing through finer materials (small 

 boulder to clay size deposits) than the troughwall landform. Many of these stream are B stream types. 



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