Sedimentary Rocks Flashcards
How do each of the three different groups
of sedimentary rock originate – detrital,
chemical, biochemical?
detrital - produced by weathering from rock of granite mountains.
chemical -formed only by inorganic means.
biochemical -sedimentary rock formed by once living organisms.
What is sediment? What are the names of
three different categories of sediments
based on grain size?
Particles of rock that are the product of weathering.
Conglomerate, sandstone, mudstone
What are the processes that occur in
order which result in the formation of
sedimentary rock?
Weathering (physical, chemical, biochemical)>
Transportation>
Deposition>
Lithification>
Diagenesis
What are the four main agents of
transportation of sediment? Which one is
most important?
Water, Air, Ice, Mass movements
Weathering is the __________. Erosion is the __________.
Breakdown ; Transportation
What are mass movements? Give
examples.
Craters from meteors. Meteor crater.
What characteristics of sediments vary
along a typical mountain-to-basin profile?
Sketch a few particles and show how they
change along such a path, and explain
why these changes occur.
At the top of the mountain, larger sediment can be found, and at the bottom, smaller sediment.
What is the geological significance of
angular and rounded gravel – that is,
what do these shapes tell us about the
transportation process that carried the
gravel particles?
The more rounded gravel is, the further it has traveled.
What is lithification?
The hardening of sediments to rock by addition of chemical cement or compaction.
What are sedimentary structures? Give
some examples.
sediment disturbed by the current of the water, that may help reveal dynamic processes of ancient enviornments, and maybe composed of valuable industrial minerals.
What are the names of some of
Alabama’s non-fuel mineral industries?
Shale, Sandstone, Sand & Gravel, Cement plants
What differences in sedimentary beds
result from the horizontal or vertical
deposition of sediments?
Horizontal-can result in crossbeds and ripples
Vertical-results in several different features preserved in a bed called normal or parallel bedding and grading.
What are ripple marks? What types of
ripple marks have been described? How
do they form? What can each of these
ripple marks tell us about the current flow
that made these features? Explain.
Wind shear on the surface of the dunes ; Asymmetrical (unidirectional) and symmetrical (bidirectional) ; They form based upon the direction of the current ;
How does cross-bedding form? Make
sure you can look at cross-bedding and
determine the direction of ancient current.
From horizontal movement.
What are graded beds? Make sure you
can look at an illustration of a graded bed
and determine which way the original UP
direction pointed.
Results from vertical settling, it is a bed that has particles of different sizes layered upon each other, with the largest at the bottom.
Mudcracks can be used to tell which way
was the original UP direction. How? Make
sure you can look at an illustration of
mudcracks and determine which way the
original UP direction pointed.
Mudcracks always curl upward!
What is permeability? Porosity? How do
these two properties control the flow of
fluids and gases in the earth?
Porosity - The measure of the void spaces in a material.
Permeability - the ability to get from one space to the other.
Greater porosity and permeability equals greater flow of fluids/gases in the earth.
How are fossils helpful in determining the
climate or other features of ancient
environments? Give some examples.
Explain.
They can determine what kind of things were around, ie. volcanoes, oceans.
How are the sediments in sedimentary
rocks helpful in determining ancient
environments? Give some examples.
Explain.
The presence of fossils, leaves, hornets.
Which type of sediment is the most
abundant in Mobile Bay?
Sand & mud
What is the “carbonate factory”? What
rock is formed there? What are the
environmental conditions of the carbonate
factory?
An area of diverse corals and other invertebrates ; limestone ; tropical climate, warm water, shallow water, clear water, biologically productive water
What does uniformitarianism mean? Give
an example of uniformitarianism.
Using the modern environment to interpret the past
The present is the key to the past
San Salvador rock in the Bahamas.
Are there any events which cannot be
investigated by strict uniformitarianism?
Give an example and explain.
Like in the case of meteor crater.
What are features of modern mudcracks?
- shrinkage crack (opens up)
- shrinkage surface (curls up)
- polygonal edges, angular intersections
How is sand related and compared to sandstone? How is sandstone related to sand?
Sand bonded together with chemical cement makes sandstone.
Sandstone weathers to sand.
This is a dynamic system.
What minerals (and their formulas) are the most common chemical cements?
Calcite (CaCO3)
Quartz (SiO2)
Hematite (Fe203)
What is chemical precipitation? Give some examples.
When water evaporates leaving behind halite. Great salt lakes is an example?
How is sedimentary rock classified? What are the names of the groups of sedimentary rocks?
Texture (size, shape)
Mineral composition
Detrital, organic or biochemical, chemical
What is sandstone? Breccia? Etc.
How is a conglomerate formed? Explain.
Gravel + cement.
If sandstone contains a significant percentage of the mineral feldspar, what is this rock named, and what can we say about the relative distance the rock traveled from the source?
Arkose
What is the name for a rock made of mud particles, and that splits into thin sheets?
Mudstone or shale
In what zone of climate and environment did (does) sediment accumulate to form limestone?
Warm, shallow, tropical waters.
+ or - 25 degrees of latitude
Give an example of sedimentary rock made from an oxide mineral.
Diatomite, Chert
What is diatomite? What is diatomite used for?
Single-celled phytoplankton, SiO2 skeletons, porous skeletons.
Filtrations, filters, absorbants, cement manufacture.
What are the two most abundant dissolved elements in sea water?
Chloride Cl-1
Sodium Na+1
What are the names of the various minerals formed by evaporation of seawater?
Halite, Calcite, Dolomite, Gypsum, Anhydrite, Sylvite
What sedimentary rocks are formed by sulfate minerals?
Anhydrite, Gypsum
Why is gypsum important in the building industry?
Is used as construction wallboard.
How is coal formed?
Wet environment/abundant vegetation -> swamp deposits of slightly decayed vegetation.
