Exam 2

At what scale is more ground covered? At what scale is detail more visible?

1:24000. 1:250,000

On a great circle a degree equals how many miles or kilometers?

1o = 69 miles = 111 kilometers = 1 nautical mile

What causes floods in the floodplain?

As widening meanders and repeated flooding deposit large amounts of alluvium, a large, very fertile floodplainis formed.Historically, floodplains have been used extensively for agriculture.Due to repeated flooding these areas may contain back swamps and small ancillary streams called yazoo tributaries.

Know what a contour line, contour interval, and index contour lines/guide contours are

Each bold line with the elevation noted is called an index contour line or guide contour.The elevation difference between every normal contour line is the contour interval

How can oxbow lakes and natural levees form

Flooding and continuous erosion may also cut across established meanders.If the resulting deposition isolates a meander, it can form an oxbow lake Once flood waters receded the deposits remain behind. Over time, regular flooding can lead to the formation of natural levees on the river banks.

How do degrees of Longitude and time compare (degrees per hour, minutes per degree

For every 15o of Longitude that one moves towards the East of the Prime Meridian, another hour has to be added to Greenwich Mean Time. For every 15o moved towards the West of the Prime Meridian, an hour is subtracted.

How did people establish Latitude on boats? What is the relation of Latitude to stellar navigation? Where can you see the North Star (Polaris) or the Southern Cross

In the Northern Hemisphere Latitude can be established by measuring the angle between the North Star (Polaris) and the Horizon.

What is a Bench Mark (BM)

In the real world elevations are measured against established bench marks, locations with a highly accurate determined elevation.On topographic maps elevations are expressed by contour lines, lines that connect all points on a map that share the same elevation.

What are degrees, minutes of arc, seconds of arc, and their units

Latitude and Longitude are expressed in degrees (o).But Coordinates expressed only in degrees are not accurate enough to establish detailed locations.Each degree of either Latitude or Longitude is divided into 60 Minutes of Arc ('), each of which is then divided into 60 Seconds of Arc (").These are not units of time.A value of 35° 43' 9" N means a Latitude value of 35 degrees, 43 minutes and 9 seconds, North of the equator.

What are meridians and parallels? Which ones run from North to South, which ones East to West

Lines of Latitude that share the same value are referred to as Parallels.The equator is the only Parallel to divide the Earth in half. Lines of Longitude that share the same value are referred to as Meridians.They run from the North Pole to the South pole.

Where is the Prime Meridian and what is its value?

Lines of Longitude that share the same value are referred to as Meridians.They run from the North Pole to the South pole. For every 15o of Longitude that one moves towards the East of the Prime Meridian, another hour has to be added to Greenwich Mean Time. For every 15o moved towards the West of the Prime Meridian, an hour is subtracted.

Which parallels are great circles? Which are small circles?

The Equator and every Meridian paired with its opposite are Great Circles. Every Parallel of Latitude other than the Equator is a Small Circle.Small Circles DO NOT bisect the Earth into two equal halves.Since the Small Circles all have different circumferences, no single conversion will apply.

Where on a low-land meandering river do erosion and deposition work the most? What do the river basins look like downstream

This also means that while weathering and erosion are dominant on the bottom of upper course river basins, as water velocity decreases downstream, deposition becomes more dominant in the lower course river basins.

In what direction in an upstream river do weathering and erosion work? What shape is the river basin in the mountains

This cross profile of an idealized river shows that from the upland head of the river (source) to the mouth(discharge site) the river channel widens and flattens out as the streamflow decreases.

What is drainage basin? How large can they be? What is the biggest drainage basin in the USA?

This surface runoff collects in streams, which then combine to form larger rivers. All the different streams, which contribute to a single river system are part of that river's drainage basin. The Mississippi River system has one of the world's largest drainage basins, its Eastern drainage divide being the Appalachian Mountains, it's Western drainage divide formed by the Colorado/Nevada Mountains.

Where would you expect river flooding to be a bigger problem, in rural or urban areas? Why

Urban

If the drainage basin is bigger, do floods become more or less likely?

less

When contour lines are close together, is the terrain steep or gently sloping

steep

What factors favor infiltration? What factors favor runoff?

1.) The porosity of the ground: Asphalt and concrete would favor runoff, loosely packed soil with vegetation would favor infiltration2.) The steepness of the gradient: The steeper the gradient, the more likely precipitation will run off.3.) The rate of precipitation: The heavier the precipitation, the likelier runoff becomes.

How do meridians pair up with their opposites in terms of values and are the results great or small circles?

A Great Circle bisects the Earth into two equal halves.The Equator and every Meridian paired with its opposite are Great Circles.On a Great Circle any distance in degrees can be directly converted into length untis as follows: 1o = 69 miles = 111 kilometers = 1 nautical mile. Every Parallel of Latitude other than the Equator is a Small Circle.Small Circles DO NOT bisect the Earth into two equal halves.Since the Small Circles all have different circumferences, no single conversion will apply

What are Latitude and Longitude

A grid system for finding your location was first proposed by ancient Greeks.Latitude values are measured towards the North Pole (90o North) and South Pole (90o South) from the equator (0o).Longitude values are measured towards the East and West of the Prime Meridian (0o) until they reach the opposite side at a Longitude of 180o.The intersection of values of Latitude and Longitude are coordinate points

What kinds of techniques are used to try and control floods?

Artificial levees, flood-control dams, and side channels can aid in alleviating the effects of river flooding

What are the USA continental time zones? What are AM and PM?

Pacific, Mountain, Central, Eastern. The word Meridian is derived from the Latin, from "meri", a variation of "medius" which denotes "middle", and "diem", meaning "day."Thus, Meridian meant "middle of the day" or "noon".Times of the day before noon were known as "ante meridian" (before noon), while times after it were "post meridian" (after noon).Our abbreviations for AM and PM are derived from these terms.

What is a base level? What is the ultimate base level. Can creating artificial base levels change the river profile?

Running water will follow the flow of gravity until it reaches base level, which can be the ocean, a lake, or an artificially created impediment to the natural river flow.Changing a river's base level alters the depositional patterns all along the course of the stream, depriving floodplains and deltas of the water and sediments they require.

What Latitude are the Tropic of Cancer, Tropic of Capricorn, Arctic Circle, Antarctic Circle

Special Parallels include the Tropic of Cancer at 23.5oN, the Tropic of Capricorn at 23.5oS, the Arctic Circle at 66.5oN, and the Antarctic Circle at 66.5oS.

What are rapids, waterfalls, meanders, oxbow lakes, yazoo tributaries, cut offs, back swamps, floodplains, natural levees and river deltas?

Sudden changes in base level, like waterfalls and rapids, are common in this area as well, as seen here in a v-shaped valley of the Yellowstone River. Close to the stream head river valleys tend to be very steep, causing streamflow to be high. This creates characteristic v-shaped stream valleys, where weathering and erosion tend to work at the bottom of the stream bed, cutting the valleys downwards and removing materials downstream. The further downstream the water travels, the more the river basin begins to curve, creating bends or meanders. As the gradient of a river becomes less steep, weathering and erosion are diverted from the bottom of the riverbed to the surface of the river, where the greatest streamflow will now occur.In any natural bends in the river, water velocity will be at its greatest, causing the bends to grow outwards into meanders.On the inside of the river bends, water velocity will be the slowest, causing deposition, further widening the meander and creating wide valleys with wide floodplains. Weathering and erosion lessens downstream. But in the meanders in the middle and lower stream profiles erosion and weathering occurs on the river surface, primarily in the outside edges of the meander, while the inside edgeswith slower streamflow become primary sites for deposition. Once flood waters receded the deposits remain behind. Over time, regular flooding can lead to the formation of natural levees on the river banks.

What are the Baseline and Townships? How are they counted and in what directions do they run?

The PLSS grid describes land areas in 6-mile intervals that created east-west tracts called townships and north-south tracts called ranges.The 6 mile by 6 mile intersection of a township and a range was called a congressional township.Each congressional township was divided into 36 1 mile by 1 mile subunits called sections.

Know what the Public Land Survey System (PLSS) is.

The PLSS was developed shortly after the revolutionary war to describe new land areas west of the Appalachian Mountains.The PLSS begins at a base point, where an east-west base line intersects with a north south principal meridian.

Over time, what happens to meanders and floodplains because of this erosion and deposition?

The increase in deposition downstream causes the river channel to become more and more smooth due to the deposited sediments.The closer to river mouth the water gets, the slower streamflow becomes, the finer the type of deposited sediment.This means along the length of the river, sediment size will decrease towards the river mouth and all deposits will be well-sorted alluvium

Understand the different kinds of map scales, fractional scales, bar scales/graphic scales

The map scale describes the relationship between the lengths on the map and the corresponding distances of the terrain depicted.The map scale is usually found in the lower margins of a topographical map and expressed in two ways: Fractional scales indicate how much the described portion of the Earth has been reduced in size on the topographical map.A fractional scale of 1/50,000 shows that one length unit on the map corresponds to 50,000 length units in the real world.The more reduced the scale, the more actual ground a topographic map can cover, but the less detail it will have. A graphic scale or bar scale is a bar divided into smaller units, which show how distances on the map correspond visually to distances in the real world.A graphic scale can be useful in determining real distances using a topographic maps through the simple use of a ruler.

Know what groundwater, aquifers, aquitards, zone of aeration, zone of saturation, the water table, and cones of depression are.

When precipitation manages to infiltrate the ground and bedrock, rather than just run off the surface it becomes groundwater,which constitutes the largest easily accessible freshwater source to mankind.As it sinks into the ground, it encounters porous rock layers, which allow the groundwater to slowly move towards the base level again. These are aquifers.To draw on groundwater one has to dig a well past the zone of aeration, where water only partially filled the pores of the aquifer, to the zone of saturation or the water table, where water has filled the aquifer completely. Some ground layers do not allow water to permeate and are called aquitards or aquicludes.On top of such layers, small water tables may form, allowing for the digging of very shallow wells.Note, that when water is drawn from an aquifer, it is usually removed faster than it can replenish, creating a cone of depression in the water table.If water is drawn fast enough, the resulting cone of depression may cause adjacent wells to go dry.

Know what caverns, sinkholes, dripstone caves, stalactites, stalagmites, and columns are.

When water flows through an aquifer made from soluble rock like limestone, the water may, over time dissolve large portions or the bedrock, creating huge underground caverns.While the water table is high, such caverns are supported by the included water. Should the water table drop below these caverns, structural support diminishes, making it possible for the cave roofs to collapse, creating sink holes. In other cases, dry caverns in limestone may still receive water from precipitation, which can cause dripstone caves.Here, evaporating water causes stalactites to grow from the ceiling, stalagmites to grow from the ground, or for them to fuse together into columns

Are there smaller units than sections in the PLSS

Yes

If you are at a certain longitude and know what time it is at the Prime Meridian, be able to determine what time it is where you are.

Yes

Where on a river profile (upstream or downstream) can you find them?

upstream