Earth Systems and Materials
• Geospheres
–Lithosphere
–Hydrosphere
–Atmosphere
• Biosphere
“Culturosphere”
“Extraterrestrial sphere”
Earth Cycles
• Geologic cycles
• Rock cycle
–how rocks form and are
transformed
• Tectonic cycle
–how mountains, continents,
ocean basins form and change
Earth Cycles (continued)
• Hydrologic cycle
–where water exists in various forms
and how it moves about
• Biogeochemical cycles
–how chemicals move through the
biosphere, lithosphere,
hydrosphere, and atmosphere
• Included: carbon and nitrogen
cycles.
Earth Materials
• Elements: most basic form of matter with
specific properties. Iron, oxygen, aluminum,
gold, etc.
• Minerals: Naturally occurring inorganic
crystalline solid with definite physical &
chemical properties. Made of elements.
Examples: quartz, biotite, calcite, galena,
etc.
– Broader economic definition: a naturally
occurring substance which can be extracted
from Earth for human use. Can be liquid or gas
and can be organic. Examples: sand, gravel,
diamond, coal, natural gas, stone.
Earth Materials (continued)
• Rocks: aggregates of minerals or
organic components.
– Igneous: derived from molten rock
– Sedimentary: made of particles of
rock or minerals and/or chemical
precipitates, and/or organic particles.
– Metamorphic: changed chemically
and/or physically in solid state from
other rocks.
Earth Materials (continued)
• Soils: several meanings
–Engineering: earth materials that can
be excavated without explosives.
–Farming: surface earth materials that
have become sufficiently weathered
to sustain rooted plants.
–Geology: “regolith” …..similar to soil
but can also be buried below surface
(“paleosol”).
Now, more about the
• Igneous Rock
Rock Cycle
– Formation processes
• Melting to form magma
• Cooling and crystallization to form igneous
rock.
Common igneous rocks include
–Basalt
–Diorite
–Gabbro
–Granite
–Rhyolite
–Andesite
None of the following rocks look much like the
others. What do all of them have in common?
• Granite
• Pumice
• Obsidian
• Basalt
• Tuff
• Pegmatite
• Andesite porphyry
• Answer: all were formed from magma!
Develop various textures*
due to
• rate of cooling,
• force of a volcanic eruption,
• presence or absence of gas,
*texture refers here to the size and
shape of the rock’s components, not to
how it feels in your hand.
RHYOLITE.
This is fine-grained (APHANITIC)
texture, which indicates rapid
cooling. The rock is:
Phaneritic
texture
indicates
slow cooling.
Here we have GRANITE, a coarse-grained
(PHANERITIC) igneous rock.
A PORPHYRY INDICATES
MULTIPLE STAGES OF
COOLING. WHICH PART
FORMS DUE TO SLOWER
COOLING?
Answer: phenocrysts
indicate slower cooling.
Larger crystals (“phenocrysts”)
contained by a finer-grained
groundmass make a PORPHYRY.
The vesicles are
gas bubbles
entrapped within
the magma as it
cools.
What develops
if the bubbles
burst?
This is a porous (VESICULAR)
Answer:
dark rock called SCORIA.
volcanic
ash
The massive glass on the left is obsidian, and the
highly vesicular rock (right) is pumice. Pumice
can be glassy, too, but is always extremely porous.
What is a unique physical property of pumice?
Answer: Pumice is the only rock which commonly
floats in water (at least until it becomes waterlogged).
Common Igneous Rocks
 Lighter color
Darker color 
Volcanic
Rhyolite
Andesite
Basalt
Plutonic
Granite
Diorite
Gabbro
 More silica
More explosive eruptions
More Fe & Mg 
Less explosive eruptions
Sedimentary Rock
• Formation processes
–Weathering : physical breakup or
chemical decomposition
–Erosion: get particles moving
–Transportation: keep particles
moving
–Deposition: particles stop moving.
–Lithification: particles get compacted
and cemented together.
Common Sedimentary Rocks
• Detrital (also known as “clastic”)
– Shale
– Sandstone
– Conglomerate (rounded clasts) and
breccia (angular clasts)
• Chemical
– limestone (some)
– Rock salt
• Biogenic
– Chalk, coal, some limestone
We can tell a lot about geologic
history by reading clues in the rock.
• Sedimentary features such as
grain size, sorting, and
stratification
• Structures such as crossbeds,
mudcracks, ripple marks.
• Fossils
• Some examples follow.
Made of at least 25% rounded
pebbles, this detrital rock is:
Answer: conglomerate
A detrital sedimentary rock made of at least 25%
angular pebbles is BRECCIA. What do angular
pebbles indicate about distance of transport from
the pebbles’ source area?
Answer: short transport distance.
A detrital sedimentary rock made
mostly of sand is (guess what)?
Sandstone (specific varietal names are also used,
such as quartz arenite, arkose, and graywacke).
A fine-grained detrital rock made mostly of
silt and/or clay is SHALE. Note the fossil.
What is it about the fine-grained clast size of
shale which makes delicate fossils common in it?
Answer:fossils are common in shale
because:
1) plant or animal tissue is likely to settle out
in the same quiet environment where silt
and clay are deposited.
2) the fine particles tend to preserve
delicate tissues better than coarser
sand or pebbles.
COQUINA, a porous mass of
broken shells.
What is a likely
environment for
this organic rock’s
formation?
Answer: a
beach exposed
to vigorous
wave action.
America’s most abundant
fossil fuel is:
Answer: COAL
Coal is an organic sedimentary
rock, although the highest grade,
anthracite coal, is metamorphic.
Fossils can tell us much about past conditions on earth.
This weird creature is a trilobite, a long-extinct group of
ocean bottom dwellers.
What does a fossil of a trilobite in
a shale indicate about the general
environment of formation of the
shale?
• Answer: the shale
was formed from mud
deposited on an
ocean floor, a long
time ago (hundreds of
millions
of years)!
Metamorphic Rocks
• Formation processes
– Parent rock
– Conditions of metamorphism
• Heat
• Pressure
• Chemical reactions
– Physical changes
• Recrystallization
• Foliation
Common Metamorphic Rocks
• Foliated
– Slate
– Phyllite
– Schist
– Gneiss
• Non foliated
– Marble
– Quartzite
–pictures
Rocks and the Environment
• Igneous Rocks
– Volcanic rocks are products of
eruptions.
– Igneous rocks can be solid such as
unfractured granitic rocks, or very
weak such as tuff (volcanic ash
accumulations…a bit of irony in the
name, isn’t there?)
• Sedimentary rocks are often
weak, notably shale, and are
the source of all fossil fuels.
Rocks and the Environment (cont’d)
• Metamorphic rocks can be
strong (unfractured gneiss
or quartzite) or weak (slate
and phyllite)
–Carbonates (limestone and
marble) tend to dissolve in
water, often leading to
sinkholes.
Rocks and the Environment (cont’d)
• Soils vary widely in
properties such as plasticity,
strength, water-holding
ability (porosity) and
permeability, expansion
/contraction tendencies, and
fertility.