Module 1 - Soil Classification Flashcards
What is the maximum mineral particle diameter in mm which is considered in textural groups?
2
Check the soil texture triangle. What texture class is soil with 30% clay and 35% sand?
A) Clay loam
B) Silt loam
C) Loam
D) Clay
A) Clay loam
Please match the pairs.
- The soil texture classes were created…
- The Unified Soil Classification System was created…
to describe the agricultural productivity of soils.
to describe soils for geotechnical purposes.
- The soil texture classes were created to describe the agricultural productivity of soils.
- The Unified Soil Classification System was created to describe soils for geotechnical purposes.
In the Unified Soil Classification System, what percentage of soils have passed a No 200 sieve to be classified as fine-grained soils?
A) exactly 50%
B) more than 40%
C) more than 50%
D) more than 60%
C) more than 50%
____ is the dominating soil order in the Southeastern US!
Ultisol
___ is the soil order you would expect in a desert environment.
Aridisol
The liquid limit of soil is determined by sieve analysis.
A) True
B) False
A) True
The soil water content at the plastic limit is lower than the water content at the liquid limit of the soil.
A) True
B) False
A) True
For how many blows is the liquid limit of a soil determined?
25
What are the climate-dominated soil types?
Gelisols, Mollisols, Aridisols
What are the Time-dominated soil types?
Inceptisols, Alfisols, Spodosols, Ultisols, Oxisols
What are the Parent Material soil types?
Andisols, Vertisols
Name the US soil taxonomy categories in order (Top down).
Order, Suborder, Great Group, Subgroup, Family, Series
What is the nature of differentiating characteristics for the US soil taxonomy category Order?
Presence or absence of major diagnostic horizons, mineralogical properties, and extremes of soil temperature and moisture regimes
What is the nature of differentiating characteristics for the US soil taxonomy category Suborder?
Soil moisture regimes and diagnostic horizons
What is the nature of differentiating characteristics for the US soil taxonomy category Great Group?
Degree of diagnostic horizon expression within each suborder taxa
What is the nature of differentiating characteristics for the US soil taxonomy category Subgroup?
Properties that intergrade to taxa in other order, suborders, and great groups or extra grade to nonsoil material
What is the nature of differentiating characteristics for the US soil taxonomy category Family?
Particle-size and mineralogy class of control section, soil temperature regime, and cation exchange activity class in most families; calcareous and reaction, depth, rupture-resistance, coating and crack classes in some families
What is the nature of differentiating characteristics for the US soil taxonomy category Series?
Any consistency identifiable soil property not specifically identified as criteria in a higher category. (any soil property considered relevant to potential uses can be recognized as a phase of soil series, i.e., slope, eroded, irrigated, drained, etc.)
How many textural classes are there in the USDA scale?
12
The USCS distinguishes between coarse-grained soils with more than 50% retained on or above the No.200 (0.075 mm) sieve and fine-grained soils with 50% or more passing the No.200 (0.075 mm) sieve.
True
Name the three main features the USCS system is based on.
Percentages of gravel, sand, and fines (fraction passing the No. 200 sieve).
The shape of the grain-size-distribution curve.
Plasticity and compressibility characteristics. In the USCS, the soil is given a descriptive name and a letter symbol indicating its principal characteristics.
