What are topographic maps?

Topographic maps are also called contour maps A topographic map is a field map where the field value is elevation. Elevation- height above sea level The isolines we draw to show the shape of the field are called contour lines

The interval we draw the lines at is called the contour interval Contour interval- the difference in elevation between two adjacent contour lines

How do we read and interpret contour maps? Where the lines are close together is a steep slope or gradient Where the lines are far apart there is a gentle slope or gradient We can calculate the gradient Gradient= change in field value/ distance

Rules for rivers Where isolines cross a stream they bend or point upstream. The river is flowing in the opposite direction that the lines point

Water flows out the opening of the “V” shape in the river Rivers always flow from high elevation to low elevation (water can’t flow up a mtn)

Hachures Hachured lines indicate a depression, a place where elevation dips or drops The first hachured line has the same elevation as the line before it- the next one goes down by the contour interval

More about hachures The first solid line inside a hachured circle also has the same elevation as the line before it as well