Soils Final Flashcards
What is Soil Structure Dependent on?
(A-PORE)
- Amount and type of Clay present
- Parent Material Type
- Organic materials present
- Recent history of management of the site and soil
- Environmental conditions under which the soil formed (local climate)
What is the classification of soil structure based on?
Grade, Form, and Size Particles
Name some Grades;
- Structureless
- Weak
- Moderate
- Strong
Name some Forms;
- Granular
- Platy
- Blocky
- Single Grain
- Massive
Name Sizes;
- Very Fine
- Fine
- Medium
- Coarse
- Very coarse
In simple terms, how does soil structure form?
Due to the action of forces that push soil particles together
Name some Grades;
Classification
- Structureless
- Weak
- Moderate
- Strong
Name some Forms;
Classification
- Granular
- Platy
- Blocky
- Single Grain
- Massive
Name Sizes;
Classification
- Very Fine
- Fine
- Medium
- Coarse
- Very coarse
How does Solonetzic Soils Develop? Into what structure?
-In very arid environments
-Accumulation of salts (Na, K, Mg) in surface horizon results in a “prismatic” structure
(Common in central interior of BC)
How does Vertisols Soils Develop? Into what structure?
-With a high smectite clay content - has a very high swell-shrink potential
-Creating strong wedged “columnar” structure
(Not com. in BC - where P.M. can be derived from weathering of basalt)
How does Basil till Form?
When a glacier advances over the landscape and plows all material that it comes in contact w/ under itself.
-Material is compressed into layers creating “lenticellular” or “platy” appearance.
Order of Sediments settling in a lake
-Sand first
-Silt
-Last in the calm of the winter, clay settles
(Resulting in stratified platy structured soil)
Whats responsible for the formation of peds?
Soil organic matter acts as an agent for building soil aggregates, particularly the polysaccharides appear to be responsible for the ped formation.
At what % slope should a Geotechnical Engineer get called in?
Anything over 60%
