phs 120 topographic map basics the sunnyslope quadrangle, arizona created by stan celestian –...

PHS 120PHS 120TOPOGRAPHIC MAP TOPOGRAPHIC MAP

BASICSBASICS

THE SUNNYSLOPE THE SUNNYSLOPE QUADRANGLE, ARIZONAQUADRANGLE, ARIZONA

Created By Stan Celestian – Instructor copyright 2005

IntroductionIntroduction: : Topographic Maps are important tools of the Earth scientist. Many features are Topographic Maps are important tools of the Earth scientist. Many features are shown on the map by the use of CONTOUR lines. A contour line is a line that shown on the map by the use of CONTOUR lines. A contour line is a line that connects points of equal elevation. The starting point (0 foot contour line) is connects points of equal elevation. The starting point (0 foot contour line) is sea level. On the topographic map these lines are shown as brown lines (sea level. On the topographic map these lines are shown as brown lines (**)) When this symbol (*) appears in the text it is your cue to press the enter key to advance to the next image.)

Created By Stan Celestian - Instructor

IntroductionIntroduction: : Contour Lines:Contour Lines: In general, note how the contour

lines are sub – parallel, they never cross or touch and they never split.

Notice also that every 5th line is a heavier line. These are called index contour lines and they are emphasized on the map to make the counting of contour lines easier.

For example the index contour directly above the 2000 line is 2100. (*)

How can you tell? You have to find out what the contour interval is. This bit of important information is located at the bottom center of the map. (*)

IntroductionIntroduction: : Contour Lines:Contour Lines:

Here is an image of the bottom of the map. There is a lot of information located here, but for now take a look at the area below the graphical scales. (*)

Below the scales it says the contour interval is 20 feet. (*)

Below this it also states: Dotted lines represent 10-foot contours. (Below that it states that the data for the contour lines was bases on

information obtained in 1929.)(*)


So, you can see that the difference in elevation from one normal contour line to the next is 20 feet. The dotted contour line is found only in the flat area of the map. (*)


Check out the position of the 1700 foot line. (*)

What is the elevation of the little unnamed hill just above it on the right side of this illustration? (*)

Back to Squaw Peak – Now that you understand that the normal contour lines are separated 20 feet from the lines above it and below it, it makes sense that every 5th line is 100 feet difference in elevation. To make it easier to count these lines the 5th line is darkened. These are the INDEX COUNTOUR lines. (*)


What is the elevation of the little unnamed hill just above it? Remember the purple line is the 1700 foot line. (*)

Summit

Going up to the summit (blue dot) of the hill, the next INDEX CONTOUR line is the 1800 foot line (red line). (*)

BUT, we are not yet quite to the summit. There are 3 normal contour lines. The next contour line would be the 1920, the next is the 1940 and the one closest to the summit is the 1960. (*)

Finally, there is one more index contour line closer to the summit. This is the . foot contour line (black) (*)1900

So, the summit of this hill is a little over 1960 feet. But it is below 1980 – otherwise there would be another contour line. (*)


While your looking at Squaw Peak, notice that the brown contour lines have different spacing. Where the contour lines are close together, there is a steeper slope. Where the contour lines are farther apart, the slope is more gentle. (*)


One last thing about contour lines is that they “V” upstream when they cross a river drainage. Check out one of the many unnamed streams on the map below. Blue represents water features on topographic maps, and the line and three dot pattern of the streams on this map indicate an intermittent stream – sometimes it flows and sometimes it doesn’t. (*)

Next, notice how the contour lines form a “V” and that the “V” points towards the top of Squaw Peak (higher elevation), The rule of thumb is that the “V’s” point upstream,(*)

There are even other drainages that are not marked by streams but simply by the pattern of the “V”s. (*)

What was done was to draw a line that connects the tips of the “V”s. As you can see, this is a good example of dendritic (branching) drainage. (*)

In this illustration of North Mountain Park (top central area of map) all the stream drainages will be highlighted in purple. It includes the blue stream lines as well as the unmarked drainage. Before you advance to the next image see if you can visualize where this additional drainage would be on just the west side of the mountain. (*)

Let’s take another look at the information at the bottom of the map. (*)

This is the name of the map and when it was created.

Photorevised means that the map was reevaluated in 1982 and that changes to the 1965 map were indicated in purple. Obviously, the map needs to be revised again. (*)


This is the location of the Sunnyslope Quadrangle with respect to the rest of the state of Arizona.

Let’s take a look at the scale next. (*)


This is the area of the two scales. (*)

The top scale is called the fractional scale:

Scale 1: 24000. (*)

This simply means that an inch on the map is equivalent to 24000 inches on the surface of the Earth. OR 1mm on the map is equivalent to 24000 mm on the Earth’s surface. (*)

One unit of ANYTHING on the map is equal to 24000 of those things on the Earth Surface. (*)


This is the graphical scale. The one you will be using in the lab is the mile scale (the top of the three scales). Note

that the total length of the scale is 2 miles. (*)

The left side of the scale is divided into 1/10’s and the right side is one mile. It is very important to note the zero in the middle. It could make a huge difference in your measurements and thus the accuracy of your answers. (*)

Some Basic Information about Topographic Maps

COLORS:

BLACK – Artificial features like buildings, dams, trails, railroad lines

BLUE – Water bodies or glaciers

BROWN – Contour lines

GREEN – Vegetation

RED – Some main roads, fences, public land system revisions

PINK – Urban areas

PURPLE - Revisions

(*)

LAKE WALES, FLORIDA QUADRANGLE (7.5 MINUTE SERIES)

Like the Mammoth Cave area, the Lake Wales area of Florida is dominated by the solution of limestone by groundwater. Here, most of the depressions are full of water. (*)

Groundwater, like surface streams, flows from areas of higher elevation to lower elevation. The water flows through the pore spaces of porous and permeable rocks.

In which direction does the groundwater flow in this area.

A hint is to look at the elevations of the lakes. (*)


The lakes are roughly the elevation of the water table. The water will flow to the lake that has the lowest elevation. (*)

Lake Wales is fairly low, but what about the others? (*)


Lake Serena is obviously at a level of 116 feet, but what about the lake to its south? (*)The contour interval here is 5 feet. So every index contour would be 25 feet. (*)

Starting with this 175 and counting down to the lake you can see the elevation of the lake is just under 125 feet.

It is higher than Lake Serena and water flows underground from this lake to Lake Serena. (*)


In a similar way, you should be able to figure out the approximate elevation of the other lakes. (*)~

119’~ 119’

~ 124’

~ 119’

~ 119’

~ 124’

~ 124’


So, based on the elevation of the water table (lake levels) the general movement of ground water is towards Lake Wales.

the endthe end

phs 120 topographic map basics the sunnyslope quadrangle, arizona created by stan celestian –...

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