Lowest and Youngest Terrace : Soil Pit #4

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Pierce Armstrong
6 years ago
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2 Lowest and Youngest Terrace : Soil Pit #4 Observations : Where : Huntington Terraces Climate : Cloudy, mid 60 s Our soil pit was the lowest of the 4 sites The pit site was located on the right side of the huntington river, looking upstream Site was on a terrace ~3 m elevation above the river Picked an area that was open space, because our terrace had an abundance of larger trees Pit was approximately 1 m 3 in size and approximately 1 m deep The area was covered in pine needles and small sticks on the surface of water There were also a few dead trees next to our soil pit site Pit Observations O Layer : Rotted pine needles on the top layer of soil Layer was ~0-5 cm thick Evidence of bioturbation from roots and dead roots, with roots of differnt assorted sizes from thin and small to thick and long Munsell System Color : 10YR 4/2 Texture consisted of silt and sandy sediment Grain size was very fine sandy and silty materials Organic materials appeared to be on the surface of the O layer with some signs about 1-2 cm below surface Faded graduated lineation from Layer O to A A Layer : Consisting of a mixture between the bottom portion of the O layer and leached B layer Layer was ~5-19 cm thick Strong evidence of bioturbation with the abundance large and medium sized tree roots in the layer, hard to dig pit Munsell System Color : 2.5Y 5/3 Sandy and silty texture consistent throughout Fine grained sand and silt material Appearance of some organic material from the O layer, some pine and smaller roots in top portion of A Layer Faint gradient line from A Layer to B Layer

3 E layer : Discontinuous patch of E layer on the backside of the pit Layer was ~15-20 cm thick White and grey sandy silt material Munsell System Color : 5PB 8/1 Also thought to possibly be ash from how fine and silty material was Faded gradient from E to B layer B Layer : Consisting of sand and dirt sediments Layer ~19-34 cm thick Oxidized soil, lighter brown and brighter rustic colors, more vibrant than rest of layers The most prominent layer in color and texture Little evidence of bioturbation from small roots Sandy and silt material very fine grain size Munsell System Color : 10 YR ⅝ Rust colored prominent horizon from oxidation Hard line lination from B layer to C layer C Layer : Parent Material, abundance of medium to larger sized stones and rocks Ranging in size from ~5-30 cm in diameter Layer consists of very rocky and sandy / silty materials, stones within the wall of the pit in the layer C No evidence of bioturbation Munsell Color System : 2.5Y 6/3 Base of layer is possible bedrock from the nearby river, with stones similar in size to the bedrock of the river Fine grain size

10 o o o o o o o

12 10/5/16 Soil Pits THIRD TERRACE Observations: Pit located on the third terrace in a flat, grassy meadow Hit parent material (gravel-cobble) at ~0.5 m Rocks are rounded and smooth Sand mixed with and below cobble Mottles of deep, rusty orange oxidation Present in A and B layers Many plant roots extending prominently down to the B layer and stopping at C 1 layer Large amount of bioturbation from ants, worms, and grubs Holes/burrows visible in the walls of the pit No visible E layer Horizons: O layer: 1 cm 10YR 3/3 A layer: 1-28 cm 10YR 3/3 Loamy sand with some coarser material well mixed (interpretation: plow layer due to homogenous layer with sharp contact between A and B layers) B layer: cm 2.5 Y 5/ 6 Medium fine sand C 1 layer: cm (color was classified even though this was the parent material and not a soil) 2.5Y 5/4 Medium sand C 2 layer: cm Gravels and cobbles Contacts: O A, gradational A B, sharp B C 1, gradational C 1 C 2, gradational

16 TOP TERRACE Observations - As we were digging, it was obvious that there were different colored soils - Lots of roots and a massive boulder - As we got deeper there were more rocks, unsorted, mostly cobble size - Once we hit parent material, it was more gray in color - There were a lot of rounded stones that seem to be eroded by water, could have been glacial till and then possibly influenced by a stream - Total depth of the hole: m - O horizon: o Depth: from 0-8 cm o color: 7.5 yr 3/3 o dark brown o roots are apparent in this layer o sandy texture o contact with horizon A is gradational - A horizon: o Depth: from 8-16 cm o Color: 10 yr 4/4 o Lighter brown than O horizon, but still dark o Sandy o Contact with E is sharp but slightly bioturbated by roots - E horizon: o Depth: from cm o Color: 2.5 yr 7/1 o White-ish gray o Sandy o Contact with B-1 is obvious due to the sudden change in color o Development of the E horizon takes time and can only be seen in well-developed soils. - B-1 horizon: o Depth: from cm o Color: 10 yr 5/6 o Yellowish brown o Roots throughout this horizon o Oxidized o We found charcoal in this horizon - B-2 horizon: o Depth: cm o Color: 2.5 y 6/6 o Semi-oxidized, not as red as the B-1 horizon - B-3 horizon: o Depth: cm

17 o Color: 10yr 5/4 o Anoxic-ish, more gray in color than the other B horizons but is still tinted red - B-4 horizon: o Depth: 41 cm- 1 m o Color: 10 yr 5/6 o Appears to be oxidized again, possible due to the plant roots that were found down there o Still sandy in texture, maybe a little silty. Picture of the hole:

18 Sketch:

Appendix A: Core descriptions

Appendix A: Core descriptions Core: Tan0706 1 Water Depth: 2550m Gear: Piston Date Collected: 6/5/07 Date Described: 7/12/10 Description and Comments: 0-23 (2.5Y 6/4), light yellowish brown. Sandy silt.