Geologic systems from an environmental
Today's lecture takes a systems approach, where
the system is definied by place, or more specifically by type
of terrane. The below is not an exhaustive list of systems. Listed
are some characteristic traits and environmental considerations.
systems from an environmental perspective:
- many different ways mountains form geologically.
- if actively forming, mountains associated
- slopes associated with high relief can generate
significant mass wasting.
- dominated by erosion and so often poor soils
from agricultuaral perspective.
- can be site of mineralization and ore bodies.
- headwaters of drainage basins (source of
- often areas of higher heatflow.
- important in determining climatic patterns.
- act as species islands, and hence very important
- most spectacular example today - Himalayan
Forum Site - a lot of information
about living in mountain environments.
Arid systems from an environmental perspective:
Photo of Death Valley Salt Flats
- > 8 inches per year (often very seasonal).
- characterized by sparse vegetation and hence
greater erosion rates.
- characterized by wind-blown deposits: sand
dunes and loess.
- groundwater of greater importance to humans
- irrigation necessary for agriculture with
soil salinization a common consequence.
- arroyos and associated flash floods a major
- produces widespread desert dust.
- more sensitive recorder of past climatic
- in terms of geohistory Nebraska, and the
western Great Plains are good examples of arid systems.
- Desert Research
Karst systems from an environmental perspective:
Above: Large spring (blue hole)
in northern Florida - an outlet for a Cave system.
Right: Photo of deposits and
fossils in sinkhole deposit at Hot Springs, South Dakota. We will
visit this site on our Black
Hills field trip this spring.
- characterized by soluble bedrock, usually
a rock type called limestone with the following types of features:
caves, and cavernous development, subsurface drainage, sinkholes,
large springs, abandoned surface drainage, terra rosa soil.
- 4 major environmental concerns:
- sinkhole collapse:
- karst terranes, because of the large surface-underground
connections, are easily polluted aquifers.
- hard water: amount of Ca++ and Mg ++ in water,
difficulties with plumbing (scale), health considerations.
- thin residual soils, terra rosas. This makes
for considerable difficulty in waste burial or disposal.
- they can be scientific treasure troves:
- as paleontologic traps, sites (see below).
- as archeologic sites.
- speleothems, cave sediments and paleoclimate
- areas with extensive karst terrane in U.S.:
- Florida ( a huge carbonate platform).
- Paleozoic limestones flanking the Ozark dome
- Valley and Ridge province, from Virginia
- Paleozoic limestones flanking the Black Hills
Cave and Karst Research Institute.
Coastal systems from an environmental perspective:
False color satellite image of North Carolina
portion of U.S. east coast, showing well developed barrier island
- a great variety of coastline types.
- wave action and other processes produce coastal
erosion and associated sediment.
- often have complex fresh-salt water aquifer
systems, and associated salt-water incursion concerns.
- sites of episodic storm related flooding
and change. Hurricanes are major shapers of the coast.
- often dynamic, shifting environments, so
landscape can change dramatically with time, especially for shorelines
such as the one pictured.
- some are place where destructive 'tidal'
waves (tsunamis) are a periodic concern.
- very bioresource rich areas.
- site where nutrient and sediment rich rivers
- port and related facilities.
- for the Gulf Coast site of fossil fuel deposits.
- sites of very high population density globally.
field trip of Rhode Island coastal environments.
- USGS Science Center for Coastal and Marine
Geology Located in
Woods Hole, MA.
Glacial systems from an environmental perspective:
Calving glacier from Hornsund,
- if over time snow fall > snow melt then
glaciers can form.
- climate dependent, polar and alpine distribution
- ice moves and glacial surges possible.
- can be associated with very destructive breakout
floods, known as jokulhaups.
- overall mass important for global sea level
changes since linked cryosphere strongly linked to the hydrosphere
- incredible record of past climatic changes
within the ice deposits.
- produce isostatic loading and unloading and
resulting crustal depression and or uplift.
- drifting icebergs are a shipping concern.
- associated permafrost (an upper freeze-thaw
zone above permanently frozen ground) produces unique engineering
- Ice Age has left extensive deposits and influenced
landforms over wide regions of the earth, including down into
Kansas, and all of northern Europe.
World Data Centre for Glaciology, Cambridge - Scott Polar Research
Biologic systems and the Gaia hypothesis:
From the Moab, Utah desert.
Surrounding the cactus is a dark lumpy and leathery surface deposit
known as a cryptobiotic crust. This turns out to be formed
by a complex assemblage of microbes, a symbiotic community. This
cryptobiotic crust is a recently recognized, very important component
of the desert ecosystem.
- marine plankton, forests, grasslands, and
crustal microbes are major ecotomes that through their aggregate
biomass and activity represent major players in surface environment
- extremophile microbes can live under much
harsher conditions (and deeper inside the earth)
- respiration of the planet evident in annual
cycles in plot of carbon dioxide with time.
- there are ecosystems independent of the sun,
but most are tied to it.
- bioremediation is one of the most effective
ways of cleaning up certain types of contaminated soil and water.
Bioremediation can be natural or enhanced.
- biodiversity a very important characteristic
of ecosystem response to changing conditions.
- Gaia hypothesis:
life in aggregate and through negative feedback loops serves
to keep surface conditions on earth so that they are favorable
for life (most critically so that they stay within the liquid
range of water).
Environmental Research Center.
of human endeavors where geoscience knowledge is used:
- natural hazard assessment: for earthquakes,
volcanic activity, landslides, floods, hurricans, radon, and
- in engineering (foundation and siting considerations).
- in resource exploration and development:
(water, energy, ores, building materials)
- in resource management and economics (estimating
- in understanding large scale environmental
changes, such as ongoing global warming.
- in legal arenas: policy advice, expert testimony,
- in other sciences: e.g. archeology
- in education.
- geoscientists are employed by diverse organizations
in diverse ways.
Geological Institute information on careers in geoscience.
D. Maher Jr. reserves copyrights to the materials in this site.
Material may be used for non-profit educational purposes as long
as proper attribution is given. For permission for any other use
please contact author. Thank you.