What are Latitudes and Longitudes?

1.Latitude values indicate the angular distance between the Equator and points north or south of it on the surface of the Earth. Note the angular distance for Latitude 45º. Check these Figures

Line of Latitudes

Line of Longitudes

How precise can we be with latitude and longitude?

A

Degrees of latitude and longitude can be further subdivided into minutes and seconds: there are 60 minutes (') per degree, and 60 seconds (") per minute. For example, a coordinate might be written 22° 30' 00" for point E.

B C

If the lat or long given in decimal format you need to convert. For example 65º 25.30’. It means 65º 25’ [0.30’ × 60’’]; that is 65º 25’ 18’’. A degree of latitude is approximately 69 miles, and a minute of latitude is approximately 1.15 miles. A second of latitude is approximately 0.02 miles, or just over 100 feet. Example: The distance from point A to B is approximately 69 miles. And the distance of E to C is approximately 17.25 miles (15 × 1.15 = 17.25).

Topographic Maps

What is the isobaths interval?

The contour interval is the difference or “jump” in

value from one contour line to its neighboring contour lines.

Each contour line represents locations where a quantity has one, specific value.

Isobath Rules:

•Isobath never touch one another (“cross”) or divide (“split”).

hill

depression

Contours in the shape of a ring represent either a hill or a depression.

Depressions are marked by hatchures

•V-Shape isobath showing a canyon under water

If the contour lines bend into a “V”-shape, then there is a ridge (high place) or trough (low place) in the data

Constructing the profile (or cross section)

Profile

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To construct a profile, follow the following steps:

Step 1: Place the edge of a sheet of paper (paper ruler) along the selected line AB or XY Step 2: Transfer the isobath markings to paper ruler Step 3: Place the paper sheet (paper ruler) with its markings above or below the blank chart (is provided)  Step 4: Depth marked on the paper ruler are carried straight upward to corresponding values on the parallel lines Step 5: Connect the dots with a smooth curve line this is your profile or cross section 

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Township, Ranges, Sections

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