arkose
-is a sandstone of intermediate maturity, somewhere between a greywacke and a
quartz sandstone.
This type of sandstone is rich in feldspar grains; 25% or more
of the rock
is feldspar. -arkose
carbonate
-is applied to both limestones and/or dolomites if one is not
sure if the material is limestone or
dolomite. -limestone, gray -dolomite from Ohio
cement
-is the fine-grained material that glues clastic fragments together to create a
sedimentary rock; the
most common, naturally occurring minerals cements that
hold clastic sedimentary rocks together
are silica (quartz) and lime (calcite).
cementation -is one of the ways in which unconsolidated sediments are converted
to solid sedimentary rocks;
the fragments are glued together.
chalk
-is an extremely soft variety of limestone, light-colored; often consists of
microscopic shells of
floating
organisms. -limestone, chalk -chalk-Opal's
Pals
coal
-is a black biologic sedimentary rock made of hydrocarbons derived from decomposed
plant
matter;
used as a fossil fuel. -coal, bituminous -coal, anthracite
compaction
-is part of the lithification process where loose sediments are consolidated into
solid sedimentary
rock due to pressure.
coquina limestone
-is a porous limestone made of crushed shells; coquina limestone resembles a petrified granola bar. -limestone, coquina
cross bedding
-is a primary sedimentary structure in which one set of inclined sedimentary layers
is beveled off
by an
erosional process and a new set of sedimentary layers is
deposited on top of the truncated
original layers;
this type of primary
sedimentary structure is common in stream sediments and
sand dunes. -cross bedding-1 -cross bedding-2
dolostone
-is a rock made out of the mineral dolomite. However, the word dolomite is also
used as the name
of the
rock made of dolomite. -dolomite from Ohio
evaporation
-is the process by which a liquid slowly transforms to a vapor.
-evaporation-Opal's Pals
graded bedding -is a layer of sediment in which the largest particles occur at the bottom of the
layer and grade
upwards
into finer materials. -graded
bedding-Opal's Pals
mud curls
-are a special form of mud cracks where the top of the mud layer has a high clay
content and the
bottom
of the layer is more silty. When the mud dries out, the
top portion of the mud layer shrinks
more that the
bottom of the layer, causing
the upper surface to curl. -mud curls
oil shale
-is a sedimentary rock made of clay that also contains substantial amounts of
petroleum.
This material is considered to be an important source of petroleum in
the future. -oil shale
peat
-is dark brown to black organic debris left from plants that grow in swampy
areas. It is the parent
material
for coal.
-peat
pebble
-is a particle size between a cobble and a granule. -sandstone pebble
physical weathering
-is the breakdown of rocks into smaller pieces without any change in chemistry;
it is also called
mechanical
weathering.
primary sedimentary structures
-are structural features found in sedimentary rocks that were created while the
sediments were still
unconsolidated. Examples include mud cracks, cross bedding,
graded bedding, layering, ripple
marks, etc. -mud
cracks -cross bedding -ripple marks-1 -ripple marks-2 -rain drop imprints
sandstone
-is a clastic sedimentary rock consisting primarily of sand grains.
-sandstone-Opal's Pals
shale
-is a sedimentary rock whose main constituent is clay. -shale, mixed colors -shale, dark gray -shale, decomposing silt -is a particle size larger than clay particles but smaller than sand grains.
This
fine grain material feels gritty but you cannot see the individual particles
with the naked eye.
sylvite
-ia a water soluble mineral that strongly resembles halite in solubility,
crystal shape, cleavage,
and taste.
However, since sylvite is not halite but potassium chloride, it has a salty
tast but is
more bitter than salt. -sylvite -sylvite-Opal's
Pals symmetric ripple marks
-are ridges of sand with equal slopes on both sides of each ripple mark.
This type
of ripple marks is caused by back and forth wave action;
they are also called
oscillation ripple marks. -symmetric ripple marks-Agate Beach, California
unconsolidated sediments
-are sediments that have not yet been converted to solid rock.
well sorted
-applies to sand grains have be sorted by a geological process, creating a deposit of sand
grains all of the same size and of one mineral.
-orthoquartzite, close up view
Chapter 6-Sedimentary Minerals and Rocks
