Exam 2 Flashcards
Understand how climate, organisms, relief, parent material, and time impact soil formation.
Relief- the shape and slope of the land affect drainage, erosion and the distribution of soil materials, steeper slopes may experience erosion and thinner soils, while flat areas can accumulate deeper soils
Parent material- underlying geological material from which soil develops, the parent material influences soil texture,, fertility, and drainage
Time- soil formation is a slow process, requiring thousands to millions of years for significant development
Why do soil properties matter?
Structure and texture affects how the soil will hold water and nutrients
How does porosity and permeability impact soil?
Porosity is the proportion of empty space so it means how close the soil is to each other and permeability is how easily fluids pass through a material which means how easily water can absorb into the soil and or how deep the water can go
What are the various measures of soil stability? Why does each matter? How do they impact
construction?
Plasticity-ability of soil to deform when a force is applied (does it break or bend, is it sticky)
strength- how well the particles stick together and resist changing shape
sensitivity-how quickly soils loses strength when disturbed compressibility-ability of a soil to compact when a weight is placed on it
shrink-swell- soils expand and contract when they get wet and dry
What is land subsidence, and what causes this problem?
Gradual sinking or settling of earth’s surface. Can happen because of groundwater extraction, soil compaction, mining activities, natural processes, melting ice, drainage of wetlands, and earthquakes
How do confined and unconfined aquifers work? Understand both recharge and discharge from these systems.
Unconfined- directly recharged by precipitation and surface water, allows water to flow freely into the aquifer, discharge occurs naturally at springs or through seepage into rivers and lakes, groundwater can be extracted through wells
Confined- sandwiched between layers of impermeable rock or clay, which restricts water movement, creates pressure, recharge is less direct and occurs in specific areas known as recharge zones, where the impermeable layers are absent, allowing water to seep in, can be slower than in unconfined due to protective layers, discharge from confined aquifers can occur when pressure causes water to flow naturally from surface, creating artesian wells or spring
Why do flowing artesian springs have water that “gushes” out of the well without the use of pumps?
Water reaches a point where the pressure is sufficient to overcome the weight of the water table and any resistance from surrounding soil and rock
How does pumping groundwater impact the water table/potentiometric surface?
The water table lowers in the well. The pressure in the aquifer lowers
What causes saltwater intrusion
Freshwater in aquifer floats on top of salt water, if a population/water demand increase, pumping increases and salt water up cones (wells can start producing salt water)
What is discharge and how do we measure discharge?
The volume of water flowing through a river or stream at a given point over a specific time period. Its measured by multiplying channel width x depth x velocity of water
Understand how the different components of rivers change downstream (channel size,
discharge, sediment load, maximum grain size)
channel size- Downstream: widest and deepest, with a gentle gradient. The river is usually meandering, and the energy is more distributed, leading to the formation of features like oxbow lakes and floodplains.
Discharge-downstream: river may carry a massive sediment load, but the type of sediment can vary, larger sediments may settle out in slower-moving waters
Maximum grain size- erosion and transport: larger sediments are more easily eroded and transported over shorter distances, as the water flows downstream, it can carry away larger particles, sorting: rivers tend to sort sediments based on size, faster-moving water at the source can carry larger grains, while slower moving water downstream tends to deposit smaller grains, deposition: in areas where the river slows down, like bends or near flood plains, larger sediments may settle out first, leaving finer materials to continue downstream
What causes erosion, transportation, and deposition? What is the difference between erosion and weathering?
Erosion-water, wind, ice, and gravity
Transportation-flowing water, wind and glaciers
Deposition-velocity changes, landform changes, glacial melting
Erosion is the prices of removing and transporting soil, rock, or sediment from one location to another and weathering is the breakdown of rocks and minerals at the earth’s surface due to physical chemical or biological processes
What are the different types of transportation in a river?
Load- the total amount of non-water material that a stream transports
Dissolved load- material that’s completely dissolved (salt in salt water)
Suspended load- material that’s not dissolved, but is light enough to be supported by the water
Bed load- material transported along the channel bed (too heavy to stay supported in the water)
Saltation load- too heavy to be “permanently” suspended, but gets suspended for short hops
Traction load- material pushed along the bottom of the channel without becoming suspended
How do meanders form?
Water moves more quickly along the outside of a channel in order to maintain parallel flow, this results in a section of the river that moves faster than everything else, the deepest section is called the Thalweg
What is the difference between a braided stream and a meandering stream?
Braided stream- multiple threaded channels that branch and merge, variable flow, high sediment load
Meandering-single curved channel, lower sediment load, stable flow
Where is the cutbank and point bar and how do these things form?
point bank is on the inside of the curve and the cutbank is on the outside
What are the most common elements that make up the earth’s crust? Are these mineral resources? How do we get mineral resources if they are rare?
Oxygen and Silicon, mineral resources, mining, exploration, extraction techniques
How do igneous processes create mineral deposits?
Minerals crystalize from melt and fall to bottom of magma chamber, minerals have different melting and crystallization points, certain minerals crystallize first, and fall to the bottom or sides of the deposit
What are Kimberlite pipes?
Form from magmas that originate from 125km below the surface (very top of mantle or base of lithosphere)
How do hydrothermal ore deposits form?
Formed by the action of hot water, which is chemically reactive, minerals crystallize from highly enriched fluids
Understand the various types of mineral deposits found around the world.
Hydrothermal- Formed by the action of hot water, which is chemically reactive, minerals crystallize from highly enriched fluids
Vein deposits- minerals crystallize within small fractures or cracks within the rock
Disseminated deposits- tiny bits of mineral crystallize out in surrounding rock as hydrothermal fluids move through it
How do metamorphic processes create mineral deposits?
During mountain building, large sections of the earth are buried deeply and heated, occurs when rising magma comes into contact with neighboring rocks and heats them up
What is asbestos and how does it impact health?
Group of naturally occurring fibrous minerals known for their heat resistance tensile strength and insulating properties, can cause lung diseases and aggressive cancers
How do sedimentary processes create mineral deposits?
Weathering, erosion and transportation
