Open Earth Systems: An
Earth Science Course
For Maryland Teacher
Professional Development
EARTH HISTORY AND THE FOSSIL RECORD
DAY 1 - Weds. July 9
AM Instruction: Solar System Origin, Early Earth & Habitability
AM Activity: Dating the Earth
PM Instruction: Major Events in Earth History
PM Activity: Exploring Geologic Time
DAY 2 - Thurs. July 10
AM Instruction: Climates of the Past
AM Activity: Weathering, Erosion and Soils
PM Instruction: The Fossil Record of Life
PM Activity: Fossil Identification
LINDA HINNOV, Instructor
Weathering of Rocks
Physical weathering is the
mechanical fragmentation
of rocks from stress acting
on them from Earth surface
processes.
Chemical weathering involves
chemical reactions between
Earth surface chemistry (water)
and minerals that progressively
decompose solid rock.
PHYSICAL
CHEMICAL
feedbacks
Famous experiment:
Griggs, 1936 heated and cooled
cubes of granite 140ºC to 30ºC
for the equivalent of 240 years of
daily fluctuations, but nothing
happened. That was dry, but with
wetting, in ~2.5 years they fell
apart !!!
Major products of weathering:
(1) fractured rock
(2) regolith (includes soil)
(3) ions in solution
Weathering of Rocks
Goldich Stability Series
“Reverse Bowen Reaction Series”
High temperature silicate minerals weather first….
Bowen Reaction Series
Weathering of Rocks
Plagioclase feldspar weathers to kaolinite ( soft white clay mineral)
Weathering of Rocks
Weathering of Rocks
Ultisols in MD
https://upload.wikimedia.org/wikipedia/commons/e/e5/Global_soils_map_USDA.jpg
http://soils.usda.gov/technical/soil_orders/
http://soils.usda.gov/technical/soil_orders/
Ultisols have an ochric epipedon (surface soil) and an argillic or kandic horizon and are commonly
calcium deficient. Most of these soils supported mixed coniferous and hardwood forest vegetation
at the time of settlement. Some are now used as cropland or pasture.
http://www.swac.umn.edu/classes/soil2125/doc/s5chp1.htm
Udults are more or less freely
drained, relatively humus poor
ultisols that have a udic moisture
regime
The udic moisture regime is common
to soils of humid climates with welldistributed rainfall, or which have
enough rain in summer so that the
amount of stored moisture plus rainfall
is approximately equal to, or exceeds,
the amount of evapotranspiration.
Water moves down through the soil at
some time in most years.
ftp://ftpfc.sc.egov.usda.gov/NSSC/E
ducational_Resources/conce
pts2.pdf
ftp://ftpfc.sc.egov.usda.gov/NSSC/Educational_
http://www.soils.wisc.edu/
Grain sizes in soil
ftp://ftpfc.sc.egov.usda.gov/NSSC/Educational_Res
ources/concepts2.pdf
USDA Soil Textural Triangle
ftp://ftpfc.sc.egov.usda.gov/NSSC/E
ducational_Resources/conce
pts2.pdf
ftp://ftpfc.sc.egov.usda.gov/NSSC/Educational_
Resources/concepts2.pdf
ftp://ftpfc.sc.egov.usda.gov/NSSC/Educational
_Resources/concepts2.pdf
Stony Run soils
completely “reworked”
(no original soil
profiles!)
Gneiss bedrock