GEOL3074: Geology for Engineers - Midterm 1

What effect did the railroad network expansion have on building stone?

It allowed for building materials to be imported in from all parts of the country, leading to the use of diverse building stone.

What has guided the development of Cincinnati?

Its geology.

What makes up the Kope Formation?

Mostly made up of shales, but has some limestone.

What caused the shallow seas in North America to drain back into the global ocean?

The Appalachian Mountain building event.

What caused the Appalachian Mountain building event?

The collision between two large continents, Laurentia and Gondwana.

What do the modern-day Appalachian Mountains represent?

They represent a small, deeply eroded remnant of the huge mountains that existed.

What do the Illinois Basin, Cincinnati Arch, and Appalachian Basin have in common?

They are products of the Appalachian Mountain building event which caused steep folding of the rocks in New York to Virginia, and a more general folding of rocks further west.

What is a feature of the Cincinnati Arch?

It is a structural high with the oldest rock layers exposed in its core and progressively younger rock layers on its flanks.

How does a pediplain form?

Forms when an eroding mountain area is at least partially buried in its own sedimentary debris.

How does a peneplain form?

Forms when the area undergoing erosion accumulates little or no sediment but is beveled down to a flat surface on top of bedrock.

What is a local example of a peneplain?

The Lexington Peneplain.

What happened to the eroded sediment from the Appalachian mountains?

They were carried oceanward by the rivers on the Atlantic Coast and the Mississippi River, which in turn creates huge tapering wedges to form emergent coastal plains and submerged continental shelves.

What happened to the eroded sediment from the Lexington Peneplain?

They were carried westward by the Ohio River and then southward by the Mississippi River accumulating in the Gulf of Mexico coastal plain and continental shelf.

What is the Birdsfoot Delta a product of?

River channelization.

What is the Atchafalaya River?

A major distributary channel where 30% of total Mississippi flow is diverted.

Name the modern day icesheets and which is the largest.

Antarctic and Greenland icesheets, with the Antarctic being the largest (10x larger than the Greenland).

When did the current day ice age start?

35 million years ago.

Another name for Ice-Contact Deposits?

Glacial Till.

Another name for Meltwater Deposits?

Glacial Outwash.

What are characteristics of Glacial Till?

- Fine-grained material called "rock flour"

- Poor sorting of material

Examples of physical structures related to icesheet movements?

Roche moutonnee, glacial striations, and glacial erratics.

What are Glacial Stiations?

Linear, mostly parallel grooves on a rock surface produced when frozen clasts embedded in the base of an icesheet are forcefully pulled over a rock outcrop.

Examples of glacial landforms?

End Moraine, Esker, and Kettle Lakes

How was the Hudson Bay created?

Laurentide icesheet was centered over the Hudson Bay which caused the crust to depress. When the ice mass disappeared, the water melted faster than the crustal rebound.

What are proglacial lakes?

Lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice.

What are the causes of the Cenozoic Ice Age?

1. Mountain building which influences atmospheric carbon dioxide levels.

2. Changes in 3 aspects of Earth's orbit which controls the distribution of solar energy across the Earth's surface.

What is eccentricity and how does it affect Earth?

Eccentricity measures how much the shape of Earth's orbit departs from a perfect circle. These variations affect the distance between the Earth and the Sun.

Where does the Ohio River begin and end?

The beginning of the Ohio River is a Pittsburg, PA with the confluence of the Allegheny and Monongahela rivers. The end of the Ohio River is when it merges with the Mississippi River near St. Louis.

Did the Ohio River exist in its present form 1 million years ago?

No, at the time the Teays River was the trunk system. (main river)

What caused the Teays river to be blocked?

The Laurentide icesheet advanced southward out of Canada and overrode and buried the lower part of the Teays River valley, causing the river to divert southward.

What path does the present-day Ohio River roughly follow?

It roughly follows the southern margin of the Laurentide icesheet.

Name the three ice sheets that reached the Cincinnati area and when did they occur?

Kansan (800,000 years ago), Illinoisan (400,000 years ago), and Wisconsian (20,000 years ago).

What happened during the Kansan Glacial Stage?

In the beginning it destroyed the Teays River and ponded water in a glacial lake through the Cincinnati area. At the end of the glacial stage, meltwater cut several deep channels known as the "Deep Stage" of the Ohio River.

Where did the "Deep Stage" of the Ohio River run?

It ran through the Little Miami River Valley, into Mill Creek and down through the Great Miami River Valley.

What happened during the Illinoisan Glacial Stage?

The icesheet advanced further and blocked portions of the "Deep Stage" river channel. This caused a lake to form through Norwood and downtown Cincinnati areas, and a spillover point developed at Anerson Ferry.

What is stream capture?

When a stream or river watershed (drainage system) is diverted from its own bed and flows instead down the bed of a neighboring stream.

What is an example of stream capture?

Maumee River, OH

What is an example of large-scale river capture?

Tennessee River.

What is a geophysical example of stream capture and explain what the example shows.

Barbed tributaries are a geophysical example of stream capture. When tributaries merge with a trunk channel, they tend to merge with it at an angle. If the flow of the trunk channel is reversed, then the tributaries are pointing in the wrong direction. This causes the tributaries to erode the surround trunk connection area, so the tributaries are flowing at the correct reversed angle.

What is an important difference between the Teays River and the Ohio River channels? What is an example of this difference?

The Ohio River is shorter in length leading to steepening of the river profile and downcutting into the landscape. The bluffs along the central part of the Ohio River's course are an example of this.

What are characteristics of lowland streams?

They have broad floodplains.

What are characteristics of upland flooding?

It is local in area, has rapid onset, and is short in duration. Upland floods are more dangerous to human life.

What are examples of flood control measures?

Artificial levees and overflow basins (retention ponds).

What is an effect of developing floodplains?

Developed floodplains have impervious surfaces that cannot soak up excess water during floods.

What effects do Urbanization have on floods?

They cause floods to be larger and to occur sooner. They also cause floods to become more frequent as well as larger.

What flood is considered Ohio's largest weather disaster and where did it impact?

The Great Flood of 1913 was considered Ohio's largest weather disaster and it impacted Cincinnati and Dayton.

What was an outcome of the Great Flood of 1913?

Increased federal support for comprehensive flood prevention and funding for flood control projects. Also caused Ohio to build multiple dams to control flooding.

What is the 1937 flood categorized as?

It is categorized as a 1-in-100-year event.

What caused the 1937 flood and how long did the flood last?

It was caused by exception rainfall, over 500% higher than normal for January. It lasted 19 days.

What are flood defense systems that Cincinnati and Covington-Newport have constructed?

They have constructed elevated levees with steel gates that are installed when a flood becomes imminent.

What are mass sediment gravity movements distinguished by?

Nature of materials, cohesiveness (related to water content), and speed of downslope movement.

What are the two axes in the Ternary Diagram (Triangle)?

The two axes that make up the diagram:

- X-axis is speed of movement with the right side being slow, and the left side being fast.

- Y-axes is water content with the bottom being cohesive, and the upper being non-cohesive.

What causes creep to occur and how does it work?

The freeze-thaw cycle causes creep. Ice expands when it freezes, causing uplift of ground surfaces. Melting of ice causes the ground surface to subside.

Name the 3 sections of a landslide and where they are located within a landslide.

The upper section of the landslide is known as the region of extending flow. The middle is known as the region of plug flow or zone of shear where there is loss of cohesion. The lower section is known as the region of compressive flow.

What are the differences between the head and the toe of a slide?

The toe exhibits compressional deformation and a mounded slide deposit. The head exhibits extensional deformation and slide scarp (steep, nearly vertical, region of exposed soil and rock).

What role do root mats play in landslides?

They accelerate downward flow of soil water, concentrating it at a weak level within the soil profile at the base of the root zone, and bind vegetation and soil material together into a cohesive mass that can slide downslope as a single unit.

What is slope loading?

Slope loading occurs where masses are placed on unstable slopes, destabilizing them.

What do the 4 areas in Ohio deemed landslide hazards have in common?

The presence of shales, which are clay formations.

What are the 6 landslides covered?

1. Clifton Heights

2. Price Hill

3. Huffman Court

4. Columbia Parkway

5. Riverside Drive

6. Mount Adams

What is the difference between Limestone and Shale when it comes to weathering?

Limestone is more resistant to weather while shales erode rapidly.

What was built after the Mount Adams landside?

There was a large retaining wall with rock bolts built.

Why did the Miami and Erie Canal become abandoned?

Canal travel was less practical than railroads. The Great Flood of 1913 and subsequent flood control measures destroyed much of the canal infrastructure.

What happened to the first settlers in Cincinnati during their first spring?

They originally built on the floodplain and their log cabins were flooded during the spring flooding of the Ohio River.

Why does the Ohio River allow geologists to gain an understanding of the stratigraphy (sequence and age of rock layers)?

The Ohio River and its tributaries provide many exposures (rock outcrops).

What do limestones tell us about the sea-level fluctuations and why?

They tell us that the water level was shallow since shallow water is more turbulent so larger deposits settle.

What do shales tell us about the sea-level fluctuations and why?

They tell us that the water level was deeper since shallow water is more turbulent so finer deposits are kept suspended until the water was less turbulent, further out, and then they would settle down.

What do the different shelves in the formation mean?

It means that the water level has changed which is indicative of the ice sheets as the ice age changes.

When were marine sediments deposited?

500 million years ago to 300million years ago (until the Appalachian uplift).

Where did North America used to be and where was Cincinnati?

North America used to be in the southern hemisphere and Cincinnati used to be south of the equator (450 million years ago).

What is the Laurentian plate?

It is the ancient North American plate.

What are characteristics of Glacial Outwash?

- Similar sand to gravel sized particles

- Often exhibit "bedforms" which record the water flow

- Denotes where the end of the ice sheet is located

What is Roche Moutonee?

Shiny, polished surface of a bedrock outcrop produced by the fine grinding action of "rock flour" carried at the base of an icesheet.

What are Glacial Erratics?

Isolated boulders found in flat-lying areas where flowing water could not possibly have moved them.

Why does mountain uplift affect climate?

Causes faster weathering by producing more sediment that reacts with and consumes atmospheric carbon dioxide.

Milankovitch Orbital Theory

1. Eccentricity - Elliptical vs. Circular (100,000- and 413,000-year cycles)

2. Obliquity vs. Tilt (41,000-year cycles)

3. Precession (23,000-year cycles)

What causes low summer insolation and what does it favor?

Small tilt + Futher away from sun (Aphelion) causes low summer insolation. This favors glaciation.

What causes high summer insolation and what does it favor?

Large tilt + Closer to the sun (Perihelion) causes high summer insolation. This favors deglaciation.

What causes the equilibrium to shift south and what happens to ice sheets?

When insolation drops the equilibrium line shifts south and the ice sheet starts to grow.

What causes the equilibrium line to shift north and what happens to ice sheets?

When insolation rises the equilibrium line moves north and the ice begins to melt rapidly.

What is Ground-Penetrating Radar and why is it important?

Ground Penetrating Radar (GPR) uses radar pulses to image the subsurface. It can help identify ancient river channels.

What did the Cincinnati area look like prior to 1 million years ago?

The Cincinnati area was a flat region (Lexington Peneplain). There was a limited amount of relief from small streams that were tributaries to the Teays River to the north.

Which glacial stage finalized the modern course of the Ohio River?

Wisconsian Ice Sheet

What happened during the Wisconsinan Glacial Stage?

It didn't lead to any changes in the Ohio River course but did erode some earlier deposited sediments and caused deposition of sediment in other parts of the established channel. It produced a large gravel bar on which downtown Cincinnati sits today.

What are other names for stream capture?

River capture, river piracy or stream piracy.

What are causes of stream capture?

- Tectonic earth movements, where the slope of the land changes.

- Natural damming, such as by a landslide or icesheet.

- Erosion (ex. headward erosion)

What is an example of stream piracy?

Shenandoah Valley, VA

What does a knickpoint?

It represents the point of stream capture.

What are characteristics of upland streams?

They have steep and narrow valleys.

What are characteristics of lowland flooding?

It is wide in area, gradually onsets, and extended in duration.

What purpose do undeveloped floodplains serve as?

They serve as sponges to soak up water during floods.

What are effects of channelization?

Confines river waters, causing intensified flooding in downstream areas.

How often does the Ohio River at Cincinnati flood?

It floods approximately every second year.

What are the 3 most important floods of the Ohio River and which was deemed the "Great Flood"?

The 1913, 1937, and 1997 floods. The 1913 flood was deemed the Great Flood of 1913.

What is the 1997 flood categorized as?

It is expected to occur between 5-10 times per 100 years.

Which of the 3 floods had the highest crest?

The 1937 flood.

What caused the 1997 flood?

It was caused by heavy rainfall over a two-day period, which caused already high spring river levels to rise even higher.

How many locks and dams are currently on the Ohio River?

There are 21 lock-dam complexes.

In order, what are the two reasons why locks and dams were built on the Ohio River?

1. Maintain navigability along the Ohio and Mississippi Rivers.

2. Flood Control

When was the first dam and lock system constructed on the Ohio River?

Beginning in the 1880s, low wooden dams with locks began to be constructed. In 1929 the lock and dam system was completed with 51 wooden wicket dams.

What are the 3 points on the Ternary Diagram (Triangle) and what do they represent?

- Bottom left represents a slide, which is fast, dry in water content making it cohesive.

- Bottom right represents creep, which is slow, dry in water content making it cohesive.

- Top represents flow, which is middle roughly fast, wet in water content making it non-cohesive.