!GLG 101-Illustrated Vocabulary-Chapter 6
!Sedimentary Minerals and Rocks
copyright 2003-Roger Weller
!amber
*an ancient, hardened tree resin often used for jewelry; preserved insects often are found
within this material..
*[Amber, Uncut-3]
*[Amber, Polished-Free Form-1]
*[Amber, Polished-Free Form-2]
!angular grain
*an unweathered grain, often with an irregular shape and sharp edges
!anthracite
*hard coal
!arkose
*a sandstone of intermediate maturity, somewhere between a graywacke and a quartz
sandstone. This type of sandstone is rich in feldspar grains; 25% or more of the rock is
feldspar.
!asymmetric ripple mark
*a ripple mark with a steep, short slope on the downstream side of its crest and a low
angle, long slope on the upstream side. This type of primary sedimentary structure is a
useful indicator of current direction of ancient streams.
*[Ripple Marks-Asymmetric-1]
*[Ripple Marks-Asymmetric-2]
*[California-Ripple Marks-1]
!bituminous coal
*soft coal
*[Coal, Bituminous]
!borax minerals
*a group of borate minerals formed as evaporites. Death Valley, California is a famous
borax deposit.
*[Colemanite]
*[Kernite]
*[Ulexite]
!breccia
*a clastic sedimentary rock made of angular fragments
*[Breccia-1]
*[Limestone breccia adjacent to an intrusion-rough]
*[Silicified breccia- #1]
!carbonate
*the phrase often applied to outcrops limestones and/or dolomites if one is not sure if the
material is limestone or dolomite.
*[Limestone, Gray-1]
*[Dolomite from Ohio]
!cement
*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
*one of the ways in which unconsolidated sediments are converted to solid sedimentary
rocks; the fragments are glued together.
!chalk
*an extremely soft variety of limestone, light-colored; often consists of microscopic
shells of floating organisms.
*[Limestone, Chalk]
!chemical sedimentary rock
*sedimentary rocks formed by mineral coming out of solution; examples include
limestone, chert, salt, and gypsum.
!chert
*a fine grained chemical sedimentary rock made of silica; often associated with
limestone. This material usually has a dull surface in contrast to the waxy appearance of
flint.
*[Chert-nodules in limestone- #1]
*[Chert, Brown-2]
*[Chert, Gray-Brown]
!coal
*a black biologic sedimentary rock made of hydrocarbons derived from decomposed
plant matter; used as a fossil fuel.
*[Coal, Bituminous]
!compaction
*part of the lithification process where loose sediments are consolidated into solid
sedimentary rock due to pressure.
!coquina limestone
*a porous limestone made of crushed shells; resembles a petrified granola bar.
*[Limestone-Coquina]
!crossbedding
*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.
*[Crossbedding-Roadcut-2]
*[Crossbedding-Roadcut-4]
!dolostone
*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
*the process by which a liquid slowly transforms to a vapor.
!evaporite
*the minerals left behind as a solution evaporates, such as salt (halite), gypsum,
limestone, and borax minerals.
*[Salt-3]
*[Gypsum, Massive-3]
*[Limestone, Gray-1]
*[Colemanite]
!fissility
*the property of a rock, such as shale or slate, of splitting into thin layers
!flint
*a chemical sedimentary rock of cryptocrystalline quartz; similar to chert but with a
waxy surface. This material chips with a conchoidal fracture, making it an ideal material
for creating arrowheads, spear points, and scrapers.
*[Flint from the cliffs of Dover-1]
*[Flint from the cliffs of Dover-2]
!fossil
*evidence of ancient life embedded in rock.
*[Brachiopod-Mucrospirifer Mucronatus]
*[Fish-1]
*[Crinoid Hash- #1]
*[Petrified Forest-Cross section of log-1]
!graded bedding
*a layer of sediment in which the largest particles occur at the bottom of the layer and
grade upwards into finer materials.
!Grand Canyon
*an extremely large and deep canyon located in northwestern Arizona; the Colorado
River flows along the bottom of the Grand Canyon.
*[Map-Arizona-Grand Canyon-1]
*[Arizona-Grand Canyon-View-6]
*[Arizona-Grand Canyon-View-4]
*[Arizona-Grand Canyon-View-2]
*[Arizona-Grand Canyon-Light Rain Falling into the Canyon]
!immature sandstone
*a sandstone made of angular grains of several minerals of various sizes (unsorted).
*[Sandstone, Graywacke]
!jasper
*a form of chert or flint that is strongly colored by iron oxides.
*[Quartz-Jasper]
*[Jasper-2]
!lake bed deposits
*mud and silt that are dumped into a lake by streams or rivers, settles to the bottom of a
lake in nearly horizontal layers.
*[Bryce Canyon-2]
*[Bryce Canyon-4]
!layering of sediments
*sedimentary rocks are commonly formed by the settling of sediments, layer upon layer.
*[Escabrosa Limestone-Roadcut1]
*[Tipped sedimentary rocks south of Tombstone]
!lignite
*soft, brown coal
!limestone
*a chemical sedimentary rock made of calcite.
*[Limestone, Gray-1]
*[Limestone-Fossiliferrous-Martin Limestone-1]
!lithification
*the process by which loose sediments are converted to solid rock either by cementation
and/or compaction
!lithographic limestone
*a very fine grained limestone, used in lithography
!mature sandstone
*a sandstone consisting of mature sand grains which are rounded, approximately all the
same size, and usually just one mineral, quartz.
*[Sandstone, Quartz Sandstone-2]
*[Sandstone-Broken Pebble]
!mudcracks
*as mud dries out, some of the water between clay particles evaporates; the surface of the
layer of mud shrinks and cracks.
*[Arizona-Rillito River-Mudcracks]
!mud curls
*a special form of mudcracks 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-Modern-Rillito River, Arizona]
!oil shale
*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.
*[Shale, Oil Shale]
!pebble
*a particle size between a cobble and a granule.
*[Sandstone, Pebble-2]
!physical weathering
*the breakdown of rocks into smaller pieces without any change in chemistry; also called
mechanical weathering.
!primary sedimentary structures
*structural features found in sedimentary rocks that were created while the sediments
were still unconsolidated. Examples include mudcracks, crossbedding, graded bedding,
layering, ripple marks, etc.
*[Mudcracks-Modern-3]
*[Crossbedding-Roadcut-3]
*[California-Ripple Marks-1]
*[Ripple Marks-Asymmetric-1]
!quartz sandstone
*a mature sandstone consisting almost entirely of similar sized, well rouinded grains of
quartz.
*[Sandstone, Quartz Sandstone-2]
!ripple marks
*small parallel ridges of sand formed by flowing water or wind.
*[Ripple Marks-Asymmetric-1]
*[Ripple Marks-Asymmetric-2]
!salt
*is the mineral halite, sodium chloride.
*[Halite]
*[Salt-1]
*[Salt-2]
!saltstone
*is the name of a sedimentary rock made of salt.
*[Salt-3]
*[Salt-5]
!sandstone
*a clastic sedimentary rock consisting primarily of sand grains.
!shale
*a sedimentary rock whose main constituent is clay.
*[Shale, Mixed Colors]
*[Shale, Dark Gray]
!silt
*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.
!siltstone
*a clastic sedimentary rock made of silt.
*[Siltstone-Various Colors]
*[Siltstone-Close Up]
!strata
*layers of sedimentary rock.
*[Abrigo Formation-1]
!symmetric ripple marks
*ridges of sand with equal slopes on both sides of each ripple mark. This type of ripple
marks are caused by back and forth wave action; also called oscillation ripple marks.
*[Symmetric Ripple Marks-Agate Beach, California]
!turbidites
*sediments deposited by turbidity flows.
*[California-Anchor Bay-1]
*[California-Anchor Bay-2]
*[California-Anchor Bay-3]
*[California-Turbidites Cut by Fault]
*[California-Turbidites-1]
*[California-Turbidites-Normal Fault]
!unconsolidated Sediments
*sediments that have not yet been coverted to solid rock.
!well sorted
*sand grains have be sorted by a geological process to create a deposit of sand grains all
of the same size and of one mineral.