Geology Notes

Atmosphere/Climate Change

Atmosphere

• The envelope of gasses surrounding the earth or another planet
• Made mostly of nitrogen and oxygen
• Energy exchanges between the sun and the lithosphere takes place
• 1 of 4 spheres of the earth

• Lithosphere: rock & soil
• Atmosphere: air
• Hydrosphere: water and ice
• Biosphere: life

Air

• Is always moving to try to equalize pressure and temperature

Greenhouse Effect

• Keeps earth at habitable temperatures
• Greenhouse gasses absorb energy from the sun and heat radiated from the ground
• Earths temperature without the GHE would be -19 C

Photochemical Smog

• Sunlight breaks up NO2 and then NO to make Ozone
• Ozone peaks mid day
• Ozone is a strong and unhealthy oxidant

Radon

• Odorless, invisible, tasteless gas
• Occurs naturally
• Not a health problem, but creates Polonium which is

Polonium

• Decays quickly and releases an energetic alpha particle which can break down DNA
• Radioactive decay radon makes polonium

Radon Exposure

• 4 picocuries is the EPA threshold for remediation
• at 4, with constant exposure your whole life, .2% get cancer after 70 years

Ozone

• stratospheric ozone absorbs ultraviolet wavelengths
• UVC makes the ozone
• UVB destroys the ozone
• CFC emit atomic chlorine and destroy ozone
• 1% decrease in Ozone leads to 2% increase in UVB, causing 2% more skin cancer

Climate

• The long term averages conditions for a given locality or region

What Effects Climate

• Amount of sunlight received
• Ocean Circulation

• Winds drive surface currents
• Oceanic gyres:

• Surface current loops in basins
• Caused by trade winds and westerlies, acted on by the Coriolis effect
• Transfer heat from equator to polar regions
• Marine upwelling along some coasts

• Thermohaline Circulation
• Reflectivity of Surface (albedo)

• Snow albedo effect

• Positive feedback
• Snow cover increases reflectivity, which makes it even colder

• Cloud albedo effect

• Negative (and positive) feedback
• Warmer temp results in more moistures/clouds – which blocks incoming solar radiation (and traps more reflected radiation)

• Topography

Variation in Climate Over Time

• Short term variations

Effects of Pinatubo

• Major volcanic eruptions block some incoming sunlight and thus cool the lower atmosphere for a few years, until the finest ash and aerosols settle out of the atmosphere
• Volcanic ash and haze in the atmosphere cools for a few years

Sun Spot Cycles

• Hot
• Plentiful during medieval warm period
• Scarce during little ice age
• Cannot explain variation since then

Variation in Climate During the Earths History

Glaciers

• Give clues about more recent climate change
• Can be used to correlate temperature with date
• Includes air bubbles→ measure greenhouse effect

Human Induced Climate Change

• Carbon Dioxide concentrations have increased from the burning of fossil fuels
• Clearing of Forests and grasslands

IPCC

• Intergovernmental panel on climate change
• Assess scientific, technical, and socio economic info relevant for the understanding of climate change
• Not a research organization
• Government org that collects and evaluates info available to make projections based on peer reviewed published literature
• Always years behind

VA geology

Physiography – west to east

Geology – by province

• Coastal plain→ unconsolidated sediments
• Piedmont→ crystalline metamorphic & igneous rocks
• Blue ridge→ crystalline metamorphic & igneous rocks
• Valley & ridge → Sedimentary rocks
• Appalachian plateau→ Sedimentary rocks

VA physiography is controlled by geology

Appalachian Plateau

• Mostly clastic sedimentary rocks
• Mostly terrestrial (above sea level) deposits
• Gently dipping and broadly folded
• Fossiliferous, may contain coal beds

Valley & Ridge

• Carbonate and clastic sedimentary rocks
• Rare igneous rocks
• Mostly marine (below sea level) deposits
• Steeply dipping, tightly folded, and faulted
• Focciliferous
• Rare coal in youngest part of section

Mesozoic Basins

• Clastic sedimentary rocks
• Igneous rocks
• Rocks are commonly:

• Terrestrial
• Gently dipping
• Fossiliferous
• Coal beds

Blue Ridge

• Intrusive and extrusive igneous rocks
• Metamorphic rocks
• Clastic sedimentary rocks
• Basement and cover rocks
• Two major metamorphic events
• Ductile faulting in basement rocks
• Brittle faulting and folding in cover rocks
• Separated from valley and ridge and piedmont by faults in most places
• Trace fossils only in youngest rocks

Piedmont

• Intrusive and extrusive igneous rocks
• Metamorphic rocks
• Several distinct terranes
• High to low grade metamorphism
• Younger intrusive rocks
• Ductile faulting and younger brittle faulting
• Complex folding is common
• Fossils are rare

Coastal Plain

• Unconsolidated sediments
• Sand rich and clay rich
• Marine and terrestrial
• Flat or gently dipping seaward
• Developed during several periods of sea level change
• Some deposits are highly fossiliferous

Mineral Resources

What do we use minerals for?