1. Chp 6: Sedimentary Rocks
Rocks initially form from solidification of magma or lava
2. These rocks subjected to weathering and erosion processes (wind,
running water, glaciers, etc) which break down those rocks into
particles.
3. These particles are then transported and settle out to become
‘sediments.’
4. These sediments are compacted to form sedimentary rocks.
5. If these sedimentary rocks are subjected to enough pressure and
heat they can then transform into Metamorphic Rocks….later Chp
…this process is known as The Rock Cycle……

2. Derivation of Sediments from Pre-existing rocks- Fig. 6-7, p.155
Figure 6.7 The derivation of sediment from preexisting rocks. Whether derived by chemical or mechanical weathering, solid particles and materials in solution are transported and deposited as sediment, which if lithified becomes detrital or chemical sedimentary rock. This illustration simply shows part of the rock cycle in greater detail (see Figure 1.14).
Fig. 6-7, p.155

3. Igneous rocks make up 90% by volume of the earth's crust.
II. Rock Types:
Igneous rocks make up 90% by volume of the earth's crust.
-Igneous rocks formed directly from molten material.
-As this molten material cools it solidifies and hardens to become rock.
- Intrusive igneous rock forms below the surface of the earth.
-Extrusive igneous rocks form from molten material that has been
forced out onto the surface of the earth (i.e. volcanoes).
Sedimentary rocks form from the accumulation of eroded debris
of other rocks or chemically from elements in seawater.
-Sedimentary rocks make up 75% of all of the rocks exposed at the
earth's surface.
-most fossilized remains are found in sedimentary rocks. This makes
sedimentary rocks useful in interpreting the earth's geologic history.
Metamorphic rocks are formed from pre-existing rocks that have
been altered as the result of intense heat and pressure.
-Metamorphism increases the “crystallinity“ and hardness of the rock;
sandstone changes to quartzite; shale changes to slate, limestone to marble.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

4. Sedimentary rocks in The Valley of the Gods, Utah
Some characteristics to note:
Layering in rocks is horizontal
Erosion has exposed layers
differentially by their lithology.
c. Red color results from iron oxide
(Fe02) cement.
d. These rocks are mostly sandstone
Sedimentary rocks in the Valley of the Gods in southern Utah. Notice that the layering in the rocks is horizontal and that erosion has exposed them in their present form. The red color results from iron oxide cement in the rocks, which are mostly sandstone. Source: Sue Monroe
Fig. 6-CO, p.148

5. Types of Sedimentary Rocks:
The type of sedimentary rock formed in an area reflects the environment
in which it was deposited, this is referred to by geologists as the facies
of the rock.
Since the facies of sedimentary beds tells the geologists so much
information about the geologic past (paleoenvironments, paleoclimates,
and past life forms), sedimentary rocks are emphasized in Historical
Geology. There are 2 basic groups of sedimentary rocks:
1. Chemical Precipitates from the evaporation of seawater, or
from the concentration of ions in water. These include rocks such as
limestone and various salts such as Halite (NaCl), Sylvite (KCl), Gypsum
(CaSO4), etc. The salts usually indicate periods of massive evaporation
of aqueous environments.
2. Clastic Sedimentary Rocks are formed from the accumulation
of debris from the weathering and erosion of other rocks. The 4 stages
of the formation of clastic sedimentary rocks (“clastic” means "broken")
are described on the following pages.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

6. IV. The Four Steps for Formation of Sedimentary Rocks:
Physical and Chemical Weathering of the “Parent Rock. This results in the
Parent rock being broken into fragments.
2. Transportation is the stage where the clastics are "moved“ (“transported”) from
the source area by water, wind, gravity, or ice.
-size of particle and distance moved very important. Larger particle requires more
energy to move that particle.
-High- energy environments would include white water mountain streams that
are capable of moving almost all sizes of particles. Low-energy environments
include lagoons, lakes, deltas, swamps, etc., that are capable of moving only the
smaller particles.
Deposition is the stage where the sediment is deposited in a particular geographic
environment, which constitutes the sedimentary environment.
-For example, large rocks formed on a mountain range would be carried down the
steep gradient and deposited at the base of the mountain if the energy of the stream
carrying them decreased when it reached the base of the mountain. Since the stream no
longer has the high energy from the gradient, the large rocks are deposited in a manner
indicative of a mountain stream environment. Sedimentary rocks can be interpreted to
find out the environment in which they formed.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

7. Sedimentary Environments can be divided into several categories:
a. Shoreline and Coastal Environments
b.“Fluvial” or Stream, River, and Delta Environments
c. Alluvial Fans or deposits at the bases of mountains
d. “Aeolian” or “wind-borne” deposits
There are numerous other sedimentary environments we will consider later….
4. Compaction is the final stage in the formation of a sedimentary rock. At this stage
the sediments are compacted due to the weight of the overburden (overlying sediments)
and can be eventually “lithified” (turned to stone) as the particles are cemented together
with substances such as Calcite (CaCO3), Silica (SiO2), or forms of Iron Oxide
(i.e. Fe2O3), among other compounds..
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

8. Depositional environments
Figure 6.4 Depositional environments. Continental environments are shown in red type. The environments along the shoreline, shown in blue type, are transitional from continental to marine. The others, shown in black type, are marine environments.
Depositional environments
Fig. 6-4, p.153

9. Red sandstone in New Mexico-note parallel, horizontal bedding
Figure 6.6 These layers of sandstone at Jemez Pueblo, New Mexico, are red because they contain iron oxide cement.
Fig. 6-6, p.155

10. V. Properties of Clastic Sediments:
These include certain characteristics of the sedimentary rock that give specific
information about the environment of deposition. These include particle size,
degree of roundness, degree of sorting, and color.
Particle Size: Clastic sediments are found in various sizes ranging from <1/256 mm
to >256 mm. Refer to Figure 1. The Wentworth Scale of Particle Sizes.
- The name of a particular sediment size is based on its particle size rather than its
Chemical composition. For example, "sand" refers to particles having a size range
Between 0.125mm – 0.5mm. There can be quartz sand such as that found along the
Gulf Coast or there may be feldspar sands, gypsum sands, etc.
-sediment size indicates the amount of energy operating in the depositional
environment and is therefore a useful clue in determining what the sedimentary
environment was. Boulders represent a high- energy environment such as a river
channel while clays represent a low energy environment such as a floodplain or swamp.
Roundness: This is simply how “round” (or smooth) the particles in the rock are.
-poorly rounded: angular, irregular shape, sharp edges.
-well rounded: Particles are smooth and have no edges.
The degree of roundness indicates either the amount of agitation the particles were
subjected to before deposition, or the length of time it took to transport the particle.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

11. The Wentworth Scale of Particle Sizes
The Wentworth Scale of Particle Sizes that is a list of sediment particle sizes and the names used to describe them:
The Wentworth Scale of Particle Sizes
Particle Name Approximate Particle Diameter in millimeters
Boulders greater than 256mm
Cobbles 64 32
Pebbles 16 8 4
Granules 2
Very Coarse Sand
1.0
Course Sand Fractional Equivalents /2
Medium Sand /4
Fine Sand
Very Fine Sand /8
/16
/32
/64
Silt
/128
/256
Clay less than 1/256
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

12. Lithification and classification of sedimentary particles
Figure 6.5 Lithification and classification of detrital sedimentary rocks. Notice that little compaction takes place in sand and gravel.
Lithification and classification of sedimentary particles
Fig. 6-5, p.154

13. a. Shale in Tenn: note how breaks along planes….called fissile…
b. Mudstone in Glacier National
Park
Figure 6.11 (a) Exposure of shale in Tennessee. Notice that the rock breaks along closely spaced planes, so it is fissile. (b) Mudstone in Glacier National Park, Montana. What do you think makes this rock red?
Fig. 6-11, p.157

14. Microscopic view of sandstone-not individual grains, about 0.5mm
what type of rounding is this-well rounded or poorly rounded?
Figure 6.8 (a) Microscopic view of sandstone showing its clastic texture consisting of fragments of minerals, mostly quartz, averaging about 0.5 mm across. How would you characterize the sorting and rounding?
Fig. 6-8a, p.156

15. Microscopic view of limestone- calcite crystals approx 1mm across
Figure 6.8 (b) Microscopic view of the crystalline texture of limestone showing a mosaic of calcite crystals that measure about 1 mm across.
Fig. 6-8b, p.156

16. Arkose: sandstone that contains pebbles and sand size grains.
Typically this rock has not been transported very far….
Figure 6.10 (b), arkose a feldspar-rich sandstone, is also fairly abundant. Iron oxides are responsible for the red parts of the rock. Source:Sue Monroe
Fig. 6-10b, p.157

17. Quartz sandstone Fig. 6-10a, p.157
Figure 6.10 (a) Quartz sandstone is the most common variety of sandstone
Quartz sandstone
Fig. 6-10a, p.157

18. Sedimentary breccia Fig. 6-9b, p.156
Figure 6.9 Detrital sedimentary rocks composed of gravel. (b) Sedimentary breccia consists of angular gravel. Source:Sue Monroe
Sedimentary breccia
Fig. 6-9b, p.156

19. Gravels deposited by swiftly flowing stream (a,b). PreCambrian (1
Billion year old conglomerate in Michigan (c) deposited same way today.
Figure 6.22 (a) Gravel deposited by a swiftly flowing stream. Most transport and deposition take place when the stream is much higher than it is in this image. (b) This nearby deposit also formed when gravel was deposited in a similar stream channel. (c) These rocks in Michigan are about 1 billion years old, yet they show features similar to those in (a) and (b). Accordingly, we are justified in concluding that this conglomerate also resulted from deposition by running water.
Fig. 6-22, p.172

20. Conglomerate: note the mixture of rounded grains and fine matrix
Figure 6.9 Detrital sedimentary rocks composed of gravel. (a) Rounded gravel is present in conglomerate. The particles in this specimen average 4 or 5 mm across.
Fig. 6-9a, p.156

21. prevents the sediments from becoming “well-rounded”.
“Well rounded” particles: subjected to a high amount of saltation (bouncing along as
they were transported) or being transported for a very long distance-such as from the
center of a continent to its shoreline. Contact with other grains doing same thing…
‘Poorly rounded’ sediments: indicate either a low amount of agitation, or a short distance
of transportation from the time the particle weathered away from their parent rocks.
A high-energy environment, allows for a long period of exposure to weathering,
such as a beach or in a stream, is conducive to the formation to the formation of
“well-rounded” sediments. On the other hand, a high-energy depositional environment
that does not allow a long period of exposure to agitation, such as an alluvial fan,
prevents the sediments from becoming “well-rounded”.
Sorting: refers to rock fragments separated according to particle size.
-“poorly sorted” sediment would contain particles of varying size. This usually
represents a rapid deposition as the result of a rapid decrease in the energy of an
environment. found in alluvial fans at the base of a mountain. This results in a
"dumping effect" of sediments at the base of the mountain (high- energy to low- energy).
Poorly sorted and poorly rounded sediment is said to be "Immature".
-“Well Sorted” sediment contains material that is made up primarily of all the
same sized particles. This indicates that the rate of deposition is slow enough to
allow the materials to be separated. This also means relatively high energy=beach.
Sediment is said to be "Mature" if it is well rounded and well sorted.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

22. Gravel on a Beach-loose aggregate of solids eroded from existing
rocks.
Figure 6.1 (a) The gravel on this beach is an example of sediment, a loose aggregate of solids derived from preexisting rocks.
Fig. 6-1a, p.150

23. Well Rounded rocks: edges are smooth and worn-NO sharp edges
Figure 6.3 Rounding and sorting in sediments. (a) Beginning students often mistake rounding to mean ball-shaped. All three of these stones are well rounded; that is, their sharp corners and edges have been worn smooth.
Fig. 6-3a, p.152

24. Well rounded, well sorted deposit-smooth edges; approx same size
Figure 6.3 Rounding and sorting in sediments. (b) Deposit of well-rounded, well-sorted gravel. The particles on average measure about 5 cm across.
Fig. 6-3b, p.152

25. Angular, poorly sorted gravel: sharp edges, particles of many sizes
Figure 6.3 Rounding and sorting in sediments. (c) Angular, poorly sorted gravel. Note the quarter to provide scale.
Fig. 6-3c, p.152

26. Gravel in outcrop- here is a sedimentary rock-bound together
by chemical cement
filling pore spaces.
Geologists call this
conglomerate
Figure 6.1 (b) The gravel in this exposure was lithified—that is, converted to sedimentary rock—when chemical cement formed in pore spaces and bound the loose particles together. Accordingly, it is the sedimentary rock known as conglomerate.
Fig. 6-6b, p.150

27. floodplains and swamps. Glauconite= marine deposition (green mineral)
Color: The color of sediment can provide useful information about a sedimentary
environment. In general, colors of sedimentary rocks can be interpreted in the
following manner:
a.) Red, yellow, brown - oxidation conditions, probably marine in origin (RUST).
b.) Black, gray, greenish-gray - reducing conditions, probably marine except for
floodplains and swamps.
Glauconite= marine deposition (green mineral)
c.) Light gray or white - little iron present, either marine or non-marine; other
characteristics of the rock must be considered such as the presence of fossils, the
type of fossils, whether or not there is cross-bedding, etc.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

28. VI. Chemical Precipitates:
Chemically formed sediments are produced under various conditions, but generally
speaking, when seawater becomes saturated with chemicals, they will precipitate out
of solution. This is similar to when a lot of sugar is added to hot tea and then it is
allowed to cool. Some of the sugar will "crystallize" or settle out of solution because
the tea was "saturated" with sugar and it could not stay dissolved. Precipitates usually
form only in low energy environments such as lagoons or deep-sea environments.
Chemical Precipitates would not be found in high- energy environments.
Limestone and Dolostone – These “carbonate rocks result from the concentration
and precipitation of Ca+, Mg+, and CO3- ions in the sea.
A. Limestone - Ca CO3 (primarily calcite)- forms offshore from the precipitation
of calcium and carbonate ions that have been dissolved off of the continents.
Limestones may also be formed from the accumulation of microscopic calcareous
tests (shells) of planktonic (or other aquatic level) micro-organisms.
B. Dolostone - Ca,Mg (CO3)2 (primarily dolomite)- forms in a similar manner, but
contains magnesium as well as calcium. Dolostone may start off as limestone and
later is subjected to groundwater replacing Ca+ with Mg+. Or, some dolostones
indicate having formed the calcium/magnesium carbonate all at once.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

29. Table 6-2, p.158

30. Core of rock salt from Michigan Fig. 6-13a, p.160
Figure 6.13 Evaporites form when minerals precipitate from evaporating water. (a) Core of rock salt from an oil well in Michigan. (b) Rock gypsum. Both rock salt and rock gypsum have many uses.
Fig. 6-13a, p.160

31. Gypsum: evaporite Fig. 6-13b, p.160
Figure 6.13 Evaporites form when minerals precipitate from evaporating water. (a) Core of rock salt from an oil well in Michigan. (b) Rock gypsum. Both rock salt and rock gypsum have many uses.
Fig. 6-13b, p.160

32. Thin layer of bedded chert
Figure 6.14 (b) Thin layer of bedded chert.
Fig. 6-14b, p.160

33. C. “Bioclastic sediments” are formed by living organisms
C. “Bioclastic sediments” are formed by living organisms. Many aquatic marine
organisms produce shells or other protective coverings by secreting calcium carbonate
(limestone) or calcium magnesium carbonate (dolomite). When these organisms die,
their shells accumulate along the sea floor forming layers of broken shell fragments.
Such material is biochemically produced and is ultimately broken by water action.
They are then referred to as "bioclastic sediments". The sedimentary rock coquina
is a good example of a bioclastic deposit. The availability of nutrients decreases the
further from the shore therefore most marine organisms live in the coastal, shallow
water areas. As the distance from shore increases, generally the number of marine
organisms decreases. The facies of bioclastic sediments such as coquina usually indicates
a lagoon to beachfront.
D. “Organic Rocks” form as the result of organics (such as vegetative matter) accumu-
lating in low energy, reducing, anaerobic environments such as swamps. The material
does not rot quickly and the volatiles are driven off leaving behind the carbon. A good
example of an organic rock is coal. The first stage is called peat. As the peat gets
compressed over time, it becomes lignite coal. As lignite becomes compressed, it
becomes bituminous coal. As bituminous coal becomes compressed, it forms the
metamorphic rock anthracite, the final stage of coal. Other types of organic rocks
may form from accumulations of dead organisms (such as fish) in low energy lagoons.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

34. Coquina-pile of shells….
Figure 6.12 (a) Present-day ooids up to 2 mm across from the Bahamas. A rock made up of lithified ooids is oolitic limestone. Three types of limestone (b, c, and d). (b) Coquina is composed of broken shells. (c) Chalk cliffs in Denmark. Chalk is made up of microscopic shells. (d) Limestone with numerous fossil shells.
Fig. 6-12b, p.159

35. Chalk cliff in Denmark-made up of skeletal remains of microscopic’
organisms
Figure 6.12 (a) Present-day ooids up to 2 mm across from the Bahamas. A rock made up of lithified ooids is oolitic limestone. Three types of limestone (b, c, and d). (b) Coquina is composed of broken shells. (c) Chalk cliffs in Denmark. Chalk is made up of microscopic shells. (d) Limestone with numerous fossil shells.
Fig. 6-12c, p.159

36. Limestone with shells Fig. 6-12d, p.159
Figure 6.12 (a) Present-day ooids up to 2 mm across from the Bahamas. A rock made up of lithified ooids is oolitic limestone. Three types of limestone (b, c, and d). (b) Coquina is composed of broken shells. (c) Chalk cliffs in Denmark. Chalk is made up of microscopic shells. (d) Limestone with numerous fossil shells.
Fig. 6-12d, p.159

37. Peat: plant remains, buried and compressed Fig. 6-15a, p.161
Figure 6.15 (a) Peat is partly decomposed plant material. It represents the first stage in the origin of coal.
Fig. 6-15a, p.161

38. Lignite: peat that has been buried deeper, compressed and heated.
Figure 6.15 (b) Lignite is a dull variety of coal in which plant remains are still visible.
Lignite: peat that has been
buried deeper, compressed
and heated.
Fig. 6-15b, p.161

39. Bituminous coal-about 80% carbon; dense, black, burns efficiently
Figure 6.15 (c) Bituminous coal is shinier and darker than lignite and only rarely are plant remains visible. Source: Sue Monroe
Anthracite=highest grade coal, 95% carbon; yields more heat than
other types of coal
Fig. 6-15c, p.161

40. Bedding or Layering of Sedimentary Materials:
Sedimentary rocks are deposited in layers known as "beds". The type of bedding will
vary depending on the environment of deposition. Under normal conditions, beds are
deposited in horizontal layers with the bedding planes (the line of contact between the
beds) parallel to one another. "Cross-bedding" occurs when the surface of deposition is
inclined (i.e. a delta) or a current is present (i.e. a stream). This type of bedding is
called "cross-bedding" and is indicative of these environments.
The types of currents that form cross-bedding strata are:
Aeolian - wind action
Fluvial - river and stream action
Marine in Origin - current action
Types of cross-bedding include planar - the bedding planes separating the cross-bedded
units are parallel, wedge - the bedding planes are at an angle to one another and form a
wedge; and trough - the bedding planes separating the cross-bedded units are curved.
Thick planar or wedge cross-bedding always indicates an aeolian (wind) deposit such
as a sand dune in the desert.
Thin planar or wedged units may be aeolian, fluvial, or marine. Because of this, other
characteristics such as color must be used to determine the environment of deposition.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

41. Principle of Horizontality
Illustration of the principles of superposition
and original horizontality
Horizontality: These sediments were originally
deposited horizontally
in a marine environment
This outcrop is Chattanooga Shale, Tennessee

42. Principle of Superposition
Illustration of the principles of superposition
and original horizontality
Superposition: The youngest
rocks are at the top
of the outcrop
and the oldest rocks are at the bottom

43. Jurassic Navajo Sandstone, Zion National Park, UT
wind blown dune deposit. Note the thickness!! the cross bedding….
Figure 6.23 Ancient sedimentary rocks and their interpretation. (a) The Jurassicaged Navajo Sandstone in Zion National Park, Utah, is a windblown dune deposit. Vertical fractures intersect cross-beds, giving this cliff its checkerboard appearance—hence, the name Checkerboard Mesa.
Fig. 6-23a, p.173

44. b. Fluvial cross bedding- originally deposited on sloping surface.
a. Bedding in sand-
shale layers.
b. Fluvial cross bedding-
originally deposited
on sloping surface.
c. Ancient cross bedding
in Montana: hammer is
30 cm long.
Figure 6.17 (a) Bedding or stratification is obvious in these alternating layers of mudrock (shale in this case) and sandstone. (b) Origin of cross-bedding by deposition on a sloping surface in a stream channel in this example. (c) Cross-beds in ancient sandstone in Montana. The hammer is about 30 cm long. Can you tell which direction the current flowed that produced this cross-bedding?
Fig. 6-17, p.164

45. Ripple Marks: form in response to flow in one direction
Cross bedding within a ripple
To and fro motion of waves in shallow water
Figure 6.19 Ripple marks. (a) Undisturbed layer of sand. (b) Current ripple marks form in response to flow in one direction, as in a stream channel. The enlargement of one ripple shows its internal structure. Note that individual layers within the ripple are inclined, showing an example of crossbedding. (c) Current ripples that formed in a small stream channel; flow was from right to left. (d) The to-and-fro currents of waves in shallow water deform the surface of the sand layer into wave-formed ripple marks. (e) Wave-formed ripple marks in sand in shallow seawater.
Current ripples in shallow stream Wave formed ripple marks in shallow seawater
Fig. 6-19, p.165

46. Lion monument in Lucerne, Switz Carved in sandstones which
illustrate cross bedding.
Also angular unconformity
with rocks above….
Howe Quarry in Wyoming, where more than 4000 dinosaurs bones were recovered.
p.167

47. VIII. The Marine Lithofacies:
1.Many times paleocurrents of water (and sometimes wind) can be traced by the ripple
marks left in some sedimentary rocks indicating ancient river channels or beachfronts.
2. Mud cracks can also be preserved indicating ancient low energy mud flats.
3. Another type of bedding is known as graded bedding. This is where there is a
gradation in the size of particles within a unit of deposition. Larger particles are found
on bottom with successively smaller sediments on top. This type of bedding is formed by
"turbidity currents", which are the sudden flows of material down the continental
slopes. This causes the finer particles to be suspended in the water while the larger
particles fall out and are deposited on the bottom with smaller and finer sediment on top.
This results in a "gradation" in particle size. Graded bedding is deep water marine facies.
VIII. The Marine Lithofacies:
This refers to the depositional sequence found in a cross section of a shore to deep-water
environment. The usual sequences of rock types are:
1. Sandstone formed on beach areas
2. Siltstone formed near-shore
3. Claystone/Shale formed further out
4. Limestone formed even further out in deeper waters
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

48. Mudcracks in ancient rocks in Montana-note cracks filled with sediment
Figure 6.20 (b) Mud cracks in ancient rocks in Glacier National Park, Montana. Notice that the cracks have been filled by sediment.
Fig. 6-20b, p.166

49. Mudcracks form in clay rich rocks-due to drying and shrinking
Figure 6.20 (a) Mud cracks form in clay-rich sediments when they dry and shrink.
Fig. 6-20a, p.166

50. Formation of graded bedding-typically found in turbidites (deep sea)
Figure 6.18 Graded bedding. (a) Turbidity currents flow downslope along the seafloor (or lake bottom) because they are denser than sedimentfree water. (b) Deposition of a graded bed takes place as the flow slows and deposits progressively smaller particles. (c) Graded bedding in an ancient stream channel where flow velocity decreased rapidly, perhaps during the waning stages of a flash flood.
Fig. 6-18, p.165

51. Bedding
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

52. that filled cavity, later filled by calcite crystals.
Some features form long after rock is deposited: note the red-brown agate
that filled cavity, later filled by calcite crystals.
Figure 6.21 Some sedimentary structures form long after deposition and tell nothing about the original depositional environment. This 50-cmlong geode formed by partial filling of a cavity by color-banded agate, which conforms to the walls of the cavity, and by quartz crystals pointing inward toward the center of the cavity.
Fig. 6-21, p.166

53. increase in sea level or a subsidence of the landmass.
Transgression: - the advancement of the sea onto the land because of a worldwide
increase in sea level or a subsidence of the landmass.
Regression: - the retreat of the sea from the land due to a worldwide drop in sea level
or the uplift of the land.
Transgressional and Regressional sequences of strata can be used to interpret and retrace
ancient coastlines.
Transgressional Sequence - reflects RISE in Sea Level
Regressional Sequence – reflects a FALL in Sea Level
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

54. Marine Transgression Marine Regression
Note vertical succession of facies in each case-they are very different
Figure 6.16 (a), (b), and (c) Three stages of a marine transgression. (d) Diagrammatic representation of the vertical sequence of facies resulting from a transgression. (e), (f), and (g) Three stages of a marine regression. (h) Diagrammatic representation of the vertical sequence of facies resulting from a regression.
Fig. 6-16, p.162

55. Marine transgression, evidence in Grand Canyon: c. Muav Limestone
b. Bright Angel shale
a. Tapeats sandstone
Figure 6.23 Ancient sedimentary rocks and their interpretation. (b) View of the Tapeats Sandstone, Bright Angel Shale, and Muav Limestone in the Grand Canyon in Arizona. These rocks were deposited during a marine transgression. Compare with the vertical sequence of rocks in Figure 6.16d.
Fig. 6-23b, p.173

56. Glacial Environments All sediments deposited in
glacial environments are collectively called drift
Till is poorly sorted, nonstratified drift
deposited directly by glacial ice
mostly in ridge-like deposits called moraines
Outwash is sand and gravel deposited
by braided streams issuing from melting glaciers
The association of these deposits along with
scratched (striated) and polished bedrock
is generally sufficient to conclude
that glaciers were involved

57. Moraines and Till Origin of glacial drift
Moraines and poorly sorted till

58. Carbonate Environments
Carbonate rocks are
limestone, which is composed of calcite
dolostone, which is composed of dolomite
most dolostone is altered limestone
Limestone is similar to detrital rock in some ways
Many limestones are made up of
gravel-sized grains
sand-sized grains
microcrystalline carbonate mud called micrite
but the grains are all calcite
and are formed in the environment of deposition,
not transported there

59. Limestone Environments
Some limestone form in lakes,
but most limestone by is deposited
in warm shallow seas
on carbonate shelves and
on carbonate platforms rising from oceanic depths
Deposition occurs where
little detrital sediment, especially mud, is present
Carbonate barriers form in high-energy areas and may be
reefs
banks of skeletal particles
accumulations of spherical carbonate grains known as oolites
which make up the grains in oolitic limestone

60. Ooids: carbonate grains deposited in high energy environment-rounded!!
Figure 6.12 (a) Present-day ooids up to 2 mm across from the Bahamas. A rock made up of lithified ooids is oolitic limestone. Three types of limestone (b, c, and d). (b) Coquina is composed of broken shells. (c) Chalk cliffs in Denmark. Chalk is made up of microscopic shells. (d) Limestone with numerous fossil shells.
Fig. 6-12a, p.159

61. Carbonate Shelf The carbonate shelf is attached to a continent
Examples occur in southern Florida and the Persian Gulf

62. Carbonate Platform Carbonates may be deposited on a platform
rising from oceanic depths
This example shows a cross-section
of the present-day Great Bahama Bank
in the Atlantic Ocean southeast of Florida

63. Mineral Resources in Sedimentary Rocks
Oil and natural gas traps: a. stratigraphic traps, b. structural traps, c. salt
dome
Figure 6.24 Oil and natural gas traps. The arrows in the diagrams indicate the migration of hydrocarbons. (a) Two examples of stratigraphic traps. (b) Two examples of structural traps, one formed by folding, the other by faulting. (c) An example of structures adjacent to a salt dome where oil and natural gas might be trapped.
Fig. 6-24, p.174

64. Alaska pipeline taking crude oil from Prudhoe Bay south to terminal.
Figure 6.25 (a) The 1290-km-long Alaska Pipeline carries oil from Prudhoe Bay to Valdez, where it is then shipped by oil tankers. The pipeline, seen here near Fairbanks, Alaska, is above ground where it crosses areas of permafrost and underground elsewhere. (b) The red line encircles the producing oil fields in the Prudhoe Bay region on Alaska’s North Slope, but discoveries have also been made in adjacent areas. This is the largest oil field in North America. It was discovered in 1968.
Fig. 6-25, p.177

65. Iron ore mined from sedimentary rocks
Economic Uses:
Iron ore mined from sedimentary rocks
Banded iron formation, Michigan. Alternating
Layers of red chert and silver colored iron minerals.
c. Iron ore mined and shaped into pellets.
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.
Fig. 6-26, p.178

66. Chp 6: Sedimentary Rocks- Summary
Sedimentary Rocks are derived from weathering of igneous rocks.
B. Two types of Sedimentary rocks:
-Chemical precipitates: Calcium carbonate
-Clastic rocks: sandstones, shales, etc.
C. 4 Steps to Formation of Sedimentary Rocks:
-Erosion: various weathering processes
-Transportation: air, glaciers, running water, etc
-Deposition
-Compaction: overburden, burial
D. Characteristics of Clastic Sedimentary Rocks
-Roundness: well rounded vs angular
-Sorting: well sorted vs poorly sorted
-Color: red=exposed to air; glauconite=green=marine
-Particle Size (see following diagram)
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

67. Table 6-1, p.152

68. Fossils commonly occur In Sedimentary rocks: Dinosaur excavation in
Wyoming.
b. Paleontologists excavating
Rhinoceros (foreground) and
Horse (background).
c. Mural showing animals
found in La Brea Tar Pits
from Los Angeles
Paleontologists excavating rhinoceros (foreground) and horse (background) skeletons from volcanic ash near Orchard, Nebraska.
Mural by Charles R. Knight showing Pleistocene mammals at the La Brea Tar Pits in Los Angeles, California, including a giant ground sloth, saber-toothed cats, a huge vulture, and a herd of mammoths in the background. p

69. Chp 6: Sedimentary Rocks- Summary
II. Chemical Precipitates
-Limestone: calcium carbonate
- Dolostone: calcium and magnesium carbonate
-Bioclastic deposits: form around remains of marine organisms.
e.g. chalk, coquina (shells),
-Evaporites: halite, gypsum, etc. Evaporitic conditions
-Coal: peat, lignite, bituminous coal, anthracite
Bedding/Layering of Sedimentary Rocks
-Aeolian: wind, cross bedding
-Fluvial: cross bedding, laminations, etc.
-Turbidites: graded bedding.
-Marine: currents-ripples
-Marginal marine to terrestrial: mud cracks
Laws of: Superposition and horizontality: oldest on bottom, flat
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

70. Chp 6-Sedimentary Rocks: Summary
Vertical Succession of Facies
-Transgressive: sea level rise
-Regressive: sea level fall
Economic Uses of Sedimentary Rocks:
-iron ore from fluvial deposits
-placer (fluvial) deposits: precious minerals-gold and silver
-Drilling for hydrocarbons (oil and gas)
stratigraphic traps, structural traps, salt domes
-gravel pits for road use

71. Chp 6: Sedimentary Rocks- Aeolian dunes
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

72. Chp 6: Sedimentary Rocks- Ripples
Figure 6.26 (a) The Empire Mine at Palmer, Michigan, where iron ore from the Negaunee Iron Formation is mined. (b) Banded iron formation at Ishpeming, Michigan. At this location the rocks are alternating layers of red chert and silver-colored iron minerals. (c) The iron ore in this region is processed and shaped into pellets about 1 cm across, and then either shipped directly to steel mills elsewhere or stored for later shipment.

73. Chert: notice the concoidal fracturing along bottom edge; hard rock,
Composed of microscopic particles of quartz.
Figure 6.14 (a) Chert is a dense, hard rock composed of microscopic crystals of quartz.
Fig. 6-14a, p.160

74. Alluvial Fans and Playa Lakes
Alluvial fans form best along the margins of desert basins
where streams and debris flows
discharge from mountains onto a valley floor
They form a triangular (fan-shaped) deposit
of sand and gravel
The more central part of a desert basin
might be the site of a temporary lake, a playa lake,
in which laminated mud and evaporites accumulate

75. Sheep Rock, ORE.: Sedimentary rocks capped by thin lava flow at top.
b. Sedimentary rocks
in Dry Fossil Beds Natl
Monument.
c. Mammals that lived in
Area from 37 to 55 million
Years ago:
1.Titanotheres
2. A carnivore
3. Ancient horses
4. Tapirs
5. rhinoceroses
Figure 6.2 Rocks in John Day Fossil Beds National Monument in central Oregon provide a record of events that took place between 6 and 54 million years ago. (a) At Sheep Rock the rocks are mostly sedimentary, but a remnant of lava flow is present on the hilltop. (b) Another exposure of sedimentary rocks in the monument. (c) Mammals that lived in the area between 37 and 55 million years ago include (1) titanotheres, (2) a carnivore, (3) ancient horses, (4) tapirs, and (5) rhinoceroses. The climate was subtropical then, but now it is semiarid.
Fig. 6-2, p.151

76. Ooids: carbonate grains deposited in high energy environment-rounded!!
Figure 6.12 (a) Present-day ooids up to 2 mm across from the Bahamas. A rock made up of lithified ooids is oolitic limestone. Three types of limestone (b, c, and d). (b) Coquina is composed of broken shells. (c) Chalk cliffs in Denmark. Chalk is made up of microscopic shells. (d) Limestone with numerous fossil shells.
Fig. 6-12a, p.159