1  Sea islands 0  (simplified grouping)                                                   
2  Coral       0
3  Backshore deposits 1 
4  Pre-Wisconsinan drift 3
5  Till, or ground moraine 3
6  Ice-laid deposits, like tg but mostly sand and silt 3
7  Thin ice-laid deposits, like ts but thin and discontinuous. 3
8  Extensive exposure of underlying Cretaceous- and 7
   Tertiary-age formations
9  Deposits of mountain glaciers 3
10 Gravel, sand and clay deposited by glacial streams adjacent to 3
   or downstream from temporary ice fronts
11 Floodplain and alluvium gravel terraces 5
12 Fan gravels 6
13 Fan sands 6
14 Pliocene-age and older stream deposits on the Great Plains 5
15 Lake deposits 2
16 Sand sheets, mostly with dunes or sand mounds at surface 1
17 Sand sheets on sandy and gravelly Ogallala Formation in 1
   southern Great Plains
18 Wisconsinan loess 1
19 Deeply weathered loess 1
20 Basalt 8 
22 Bedrock 7
23 Micaceous residuum without much quartz; clay, 4
   mostly kaolinite
24 Residuum with abundant quartz; much less mica than rsh, but 4
   equal to clay
25 Clay residuum with little mica or quartz; mostly massive 4
   kaolinitic clay
26 Red clay, massive clay that is generally kaolinitic 4
27 Cherty red clay; similar to rls, but with chert from the 4
   parent rock
28 Residuum on Triassic-age formations; depths less than most 4
   other saprolite, reddish color, largely inherited from
   from parent rock
29 Sandy residuum, derived by intensive weathering of sandstone 4
   formations. Sand locally is in dunes
30 Clay residuum that swells when wet; developed by weathering 4
   of poorly consolidated shale, containing the clay mineral
   montmorillonite, generally less than 10 feet
31 Loam; texture variable, ranging from sand to clay, mostly 4
   non-swelling clay mineral, kaolinite; otherwise similar to rc
32 Intensively weathered upper Tertiary- and Quaternary-age 6
   gravels; thickness generally less than 30 feet,
   distribution not completely known
33 Phosphatic clay; poorly sorted clay and phosphate pebbles or 4
   nodules in sandy matrix. Thickness 10 to 50 feet, commonly
   overlain by loose sand. Major source of phosphate fertilizer
34 Sandy or silty residuum; probably includes loess. Depth 4
   generally less than 10 feet
35 Silt on limestone; probably includes considerable loess; 7
   extensive bare rock
36 Sandy ground; mostly on poorly consolidated sandstone 7
   formations
37 Shaley or sandy ground; on mixed sandstone and shale 7
   formations; where shaley, contains considerable swelling clay
38 Sandy gypsiferous ground; many sinks, local dunes; vegetation 1
   scanty or lacking where there is much gypsum or other salt
39 Clayey ground on weathered Permian- and/or Triassic-age 7
   red beds
40 Marshes, swamps, peat deposits; only locally thicker than 12 2
   feet
41 Sandy coastal ground with organic layer over a shallow water 1
   table, ground water podsols
42 Sandy and stony colluvium derived mostly from sandstone and 4
   shale
43 Stony colluvium on limestone; considerable admixed silt, 4
   possibly of loess origin
44 Stony colluvium on metamorphic rocks; less silt and clay than 4
   in co/ls
45 Colluvium on volcanic rocks 4
46 Bouldery and sandy colluvium on granitic rocks 4
47 Clayey and loamy colluvium; on poorly consolidated rocks on 4
   lee sides of Pacific Coast Ranges