Earth Mat Flashcards - Ch 12 Pt 2

Question 1

Which soil order would likely form under reducing environment and may contain sulfide minerals such as pyrite (FeS2)
- Histosol
- Aridosol
- Ultisol
- Gelisol

Answer 1

Histosols

Question 2

Small clumps of partially inundurated material due to mineral precipitation

Answer 2

Soil Peds

Question 3

Truly solid crusts produced by mineral precipitation

Answer 3

Durisols, Petrosols

Question 4

Weathering of bedrock generates in situ

Answer 4

residual soils

Question 5

Further weathering of such transported sediments generates

Answer 5

transported soils.

Question 6

is a term used for soils that contain subequal propotions of sand and silt and signifi cant amounts of clays.

Answer 6

Loam

Question 7

The USDA-NRCS divides soil horizons into

Answer 7

epipedons

Question 8

The B horizon is also known as

Answer 8

Zone of Illuviation

Question 9

In many cases, mineral precipitation in the B-horizon binds soil particles together into hard, nodular zones or into completely indurated sub - horizons called

Answer 9

duricrusts

Question 10

Calcium Carbonate duricrusts in caliche soils

Answer 10

Calcrete / petrocalcic horizons

Question 11

Duricrusts of silica? gypsum?

Answer 11

Silcretre; Petrogypsic

Question 12

are partially cemented clods of soil particles of various sizes that give the soil a crumbly lump appearance.

Answer 12

Peds

Question 13

concentrations of illuviated material such as clays or iron oxides that occur as layers or that envelope less - altered cores.

Answer 13

Cutans

Question 14

prolate to equant hard lumps formed by mineral precipitation and include concretions and nodules of all sizes.

Answer 14

Glaebules

Question 15

Heirarchy of Soil Classification

Answer 15

Orders, Suborders, Great groups, Sub Groups, Families, Series
On Sunny Green Slopes, Flowers Shine

Question 16

How many Orders are there in the USDA-NRCS classificatio

Answer 16

12 major orders

Question 17

Gray to brown A - horizon epipedon;
B sub - horizons rich in clays with reasonably high concentrations of bases such as Ca, Na, Mg;
reasonably high moisture content

Answer 17

Alfisols

Question 18

Weak horizon development; rich in disordered clays and Al – humus complexes;
high phosphorous retention;
good moisture capacity and cation exchange capacity

Answer 18

Andisols

Question 19

Sparse organic material in A - horizon epipedon;
well - developed B - horizons, often rich in Ca - carbonates, even gypsum;
low moisture content for long periods of time

Answer 19

Aridosols

Question 20

Lack signifi cant soil horizon development;
soils only because they have the capability to support rooted plants;
often sand rich

Answer 20

Entisols

Question 21

Permafrost soils and soil features;
patterned ground, broken horizons and incorporation of organic matter in lower horizons produced by frost heaving and churning

Answer 21

Gelisols

Question 22

Mostly very organic rich O - horizon;
deeper horizons tend to be poorly developed, if at all

Answer 22

Histosols

Question 23

Weak horizon development; less clay concentration in B - horizon than alfi sols;
carbonate and silica - rich B - horizons may occur;
reasonably high moisture content

Answer 23

Inceptisols

Question 24

Very dark, thick, organic - rich O and A epipedon;
high base content, especially calcium;
clays with high cation exchange potential

Answer 24

Mollisols

Question 25

Weak horizon development; extreme decomposition and base depletion; clays, mostly kaolinite, with low cation exchange capacity; bauxite under extreme conditions; quartz and iron oxides

Answer 25

Oxidation

Question 26

Thick O - horizon; well - leached A - horizon with low Fe, Al, Ca; well - developed B - horizons with clays, reddish iron oxides or black humic material; good cation exchange

Answer 26

Spodosols

Question 27

Well - leached A - horizon with some organics; clay - rich B - horizons with generally low base contents as Ca, Na and K are largely removed which distinguishes them from alfisols

Answer 27

Ultisols

Question 28

High expansive clay content; large changes in volume associated with wetting and drying; cracks when dry and other evidence of soil movement; may have horizons

Answer 28

Vertisols

Question 29

soils that contain more than total 50% sand and gravel

Answer 29

coarse grained soils

Question 30

Subdivision of coarse grained soils and characterisitcs

Answer 30

Clean Soils : <5% fines Dirty Soils : >12% fines

Question 31

contain more than 50% silt plus clay.

Answer 31

Fine - grained soils

Question 32

is the amount of stress a soil can bear without failing by rupture or plastic flow

Answer 32

Soil strength

Question 33

Soil sensitivity in response to water content, easily determined in the lab, is commonly expressed by

Answer 33

Atterberg limits

Question 34

Atterberg Classes

Answer 34

Brittle solids Semi Solid soils Plastic soils Liquid Soils

Question 35

Boundary between brittle and semi solid soilds Water contnet below which solids do not shrink

Answer 35

Shrinkage Limit (SL)

Question 36

Separates semi solids to plastic soils deformation changes from rupture to plastic

Answer 36

Plastic Limit (PL)

Question 37

The _of a soil is a measure of its cohesiveness, which is sensed as a sticky, cohesive feel to the touch.

Answer 37

plasticity

Question 38

Separates liquid to plastic soils soils lose shear strength

Answer 38

Liquid Limit (LL)

Question 39

of a soil is the range of water contents over which the soil behaves as a plastic substance

Answer 39

The plasticity index (PI)

Question 40

expresses the tendency of soils to change volume when wetted

Answer 40

Shrink – swell potential

Question 41

plot of plasticity index versus liquid limit that is used extensively in laboratory testing of fine - grained soils.

Answer 41

Casagrande diagrams

Question 42

Hydraulic conductivity of sediment types

Answer 42

Clays: ∼ 10⁻⁶ cm/s Silts: ∼ 10⁻⁴ cm/s Sands: ∼ 10⁻² to 10⁻³ cm/s Gravels: ∼ 10⁻¹ to 10¹ cm/s

Question 43

Buried soils that have been uncovered and exposed at Earth ’ s surface by subsequent erosion are called

Answer 43

exhumed soils

Question 44

are ancient soils that formed under conditions not related to the present climate.

Answer 44

Paleosols

Question 45

Depressed C13/C12 in soils indicate; the opposite?

Answer 45

presence of organims and cooler temperatures; greenhousr atmosphere, higher temperature

Question 46

how did the rise of Mollisols in the Eocene led to Pleistocene glaciations

Answer 46

Grasses sequester greenhouse gases, removing CO2 from the atmosphere. Causes coeval long term global cooling eventually leading to glacations.