1. Environmental Geology, Processes, Minerals & Soils
Unit 8
Environmental Geology,
Processes, Minerals & Soils

2. Geology
Geology is the study of the Earth’s dynamic process with respect to it’s interior and surface structure and features. Rocks, minerals, chemicals, earthquakes, and volcanoes are studied to reveal information about our planet.
Review the handout from Chapter 6 on the geosphere.

3. Geosphere
Core – central, innermost part of the Earth with a solid part surrounded by hot, liquid molten material
Mantle – thick solid region that surrounds the core and has zones of molten rock that flows (asthenosphere)
Crust – thin, outermost region of the geosphere
**Note that the lithosphere is composed of the upper mantle and the crust!

4. Plate Tectonics
Tectonic plates – constant movement of the rigid plates due to heat (energy) flow of materials
Plate tectonics is the theory that explains the movement of the plates and the processes that occur at their boundaries
Plate motion has produced mountains, ocean ridges, trenches and other features
Plate movement provides many minerals we use as resources
Continental drift helps to explain migration and evolutionary patterns

5. Global Geological Information
Internal process that occur under the Earth’s surface
See figure 12-3 (a) for a map of earthquakes and volcanoes along bands on the earth
See figure 12-3 (b) for a map of plate boundaries

6. Plate Boundaries
Divergent plate boundaries – plates move in opposite directions
Convergent plate boundaries – plates move toward each other
Transform faults – plates that slide past each other

7. Erosion & Weathering
External process that happen on the Earth’s surface
Erosion is the process where matter is dissolved, loosened or worn away from one place to another (ex. streams)
Weathering is the mechanical or chemical process that provides change to the surface matter
Mechanical – physical changes (ex. frost wedging)
Chemical – decompose by reaction (ex. acid rain)

8. Rocks
Minerals – elements & inorganic compounds that occur naturally (ex. gold)
Rocks – large continuous part of the earths crust & many consist of 2 or more minerals
Rock types – 3 broad classifications are:
Igneous – formed from molten rock (ex. lava)
Sedimentary – impaction of sediment (ex. shale)
Metamorphic – rock that has been subjected to high temperature, high pressure, chemical activity or a combination of these (ex. marble)

9. Rock Cycle
The rock cycle is the interaction of processes that continuously change rocks over time
Recycles materials over millions of years
Slowest of all Earth’s cycling processes
Concentrates the Earth’s non-renewable resources

10. Mineral Resources
Non-renewable resources – mineral resources that take millions to billions of years to occur
Ore is mineral resources mined for profit
Metallic mineral – ex. iron & copper
Nonmetallic mineral – ex. salt & clay
Energy resources – ex. coal & oil

11. USGS Mineral Catagories
The USGS has 4 classifications for non-renewable mineral resources
Identified resources – known location, quantity and quality
Undiscovered resources – assumed to exist with unknown data
Reserves – identified resource that can be extracted and sold for a price
Other reserves – undiscovered and identified resources that are not classified as reserves

12. Detection Methods Several methods are used to detect minerals
Aerial photos & satellite images - outcrops
Radiation-measuring equipment – detect deposits
Magnetometer – record changes in the Earth’s magnetic field
Gravimeter – measures differences in gravity due to density differences in various ore deposits
Underground methods – deep well drilling & core samples
Seismic surveys – analyzing shock waves by detonation
Chemical analysis – leaching into water & plants

13. Mining
Surface mining – equipment strips away the surrounding and unwanted material called the overburden (as waste it is called “spoil”)
open-pit mining – equipment digs a hole & extracts ore
Dredging – draglines scrape up underwater minerals
Area strip mining – terrain flattened prior to digging
Contour mining – cuts terraces into the terrain
Mountain-top removal – explosives & powerful shovels expose ore
Sub-surface mining – deep vertical shafts, explosives, heavy equipment used for extraction

14. Environmental Impacts of Mining
Scarring & disruption of terrain
Collapse of land above mines
Toxin laced mining waste & air pollution
Acid mine drainage
Overall effects on the health of humans and wildlife can be devastating

15. Mineral Supply
Economic depletion – cost is more to find and process than its worth on the open market
Recycle or reuse
Waste less
Use less
Find a substitute
Do without
Depletion time = depletion /time
“Should we continue to mine?”

16. General Mining Law of 1872 $500 payment & $100/20acres
Management of timber & minerals
Opens land for mineral development
Sell off mineral rich public land
Turn management over to state & local governments

17. Mining Lower Grade Materials
Achieved with current technologies
Can be limited by
Increase cost of mining large quantities of ore
Availability of fresh water
Environmental impact of increased waste & pollution
Environmental impact of disrupting the ecosystem surrounding the mine

18. Microbes in Mining
Bio-mining or in-situ mining is done by inoculating an ore vein with microbes that act on a specific ore
Microbe loosens the ore and provides a means to extract it by flooding the mine
Flood water is filtered for the desired ore and recycled back to the mine
Ex. Copper ore is digested by thiobaccillus ferroxidans
Bio-mining is a slow process

19. Natural Hazards An ecosystem can be disrupted by natural hazards
Volcanic eruption
Hurricanes
Tornadoes
Earthquakes
Floods
Do the Natural Hazards Lab
Prepare a poster or Power Point presentation that compares & contrasts 2 natural hazards

20. Soil Resources Complex mixture of Renewable resource Eroded rock
Mineral nutrients
Decayed organic matter
Water
Air
Organisms (decomposers)
Renewable resource

21. Mature Soil – Soil Zones
Soil Profile – cross section view of the horizontal zones in the soil O * Surface covered with leaves
A * Top soil is composed of a porous mixture of decomposed matter and minerals
B * Sub-soil composed of rocks and other inorganic matter
C * Parent mineral which lies above the bedrock

22. Soil Types
Infiltration – water percolates (seeps) into the zones of soil
Leaching – water picks up minerals as it infiltrates and carries them to lower zones
Soil types in different locations
Desert
Grassland
Tropical rainforest
Deciduous forest
Coniferous forest

23. Soil Permeability & Porosity
Soil permeability – the rate at which water infiltrates the soil
Soil porosity - # of pores/volume of soil
Loams is best for growing crops & contain equal parts of
Clay – holds water
Sand – drains easily
Salt - minerals
Humus – organic matter

24. Soil pH and Nutrient Concentration
Acidity (acidic) – pH is between 1-6.5
If too acidic, neutralize with lime & fertilize
Neutral – pH is around 7
Alkalinity (basic) – pH is between 7.5 – 14
If too basic, add sulfur
Perform the soil lab

25. Soil Erosion Movement of soil from place to place Loss of fertile land
Build up of soils on land and in water
Erosion is occurring faster than soil can form
Globally -15% erosion total and 40% of the agricultural property has eroded
US - 1/3 of the prime soil in the US has eroded
USDA states the soil is eroding 16x faster than it forms
USDA states conservation efforts are working

26. Desertification
Desertification is the process of turning fertile land into desert
Drought – long periods without precipitation
Unsustainable human activity – lack of conservation efforts and respect for our land
Overgrazing
Deforestation
Surface mining
Erosion
Salination
Soil compaction

27. Salination Salination occurs with a concentration of salts in the soil
Irrigation containing salts in the water
Evaporation and transpiration processes leave salts behind
Salts build up to a critical level

28. Waterlogging
Waterlogging occurs when there is too much water remaining on land
Precipitation & irrigation percolates downward
Water table (underground water levels) rise

29. Soil Conservation
1985 Farm Act – strategy to reduce soil erosion in the US
Reduce erosion & restore fertile land
Conservation tilling – disturb soil as little as possible
Terracing – reduce erosion on slopes
Contour farming – plant along contours of gentle slopes
Strip cropping – planting alternate strips of crops
Alley cropping – planting between shrubs and trees
Wind breaks – planting a row of trees or shrubs on perimeters
Gully reclamation – fast growing vines and shrubs

30. Restoring Soils Organic material
Animal – dung, adds nitrogen to the soil and stimulates bacterial & fungial action
Green manure – green vegetation tilled into the soil
Compost – rich organic matter produced by bacteria from decomposed organic matter in the presence of oxygen

31. Important Nutrients Commercial fertilizers contain:
Nitrogen (N) – important for protein production in plants
Potassium (K) - potash – primary agricultural nutrient for food crops
Phosphorous (P) – phosphates - essential nutrient from rocks
Soil Lab