Topographic Maps What is a topo map The

Topographic Maps

What is a topo map? • The shape of the earth is shown by contour lines • Contour lines connect places of equal elevation

• Show the height of a mountain, the depth of the ocean, the steepness of a ridge

http: //yellowmaps. com/maps/berg_lake_topo_map. htm

Main Ideas • Lines are continuous – that is, they never cross or branch • The closer they are together, the steeper the terrain Steep hill – lines are close together Not as steep – lines are not as close

• Lines crossing a stream always point upstream toward the headwaters • Remember the headwaters is where the river starts at the top of a mountain • So, they point away from the direction the river is flowing

• A mountain ridge is opposite to a river • On a ridge, the lines point downhill

Grid References • Topographical maps show contour lines, but also have a grid that is used to find absolute location Heading north Heading east http: //timetrail. warwickshire. gov. uk/toolkitview. aspx? tid=2&page=52

Find and name the location of a square on a grid • • • East FIRST North SECOND So, what is 1? Go to the left of object (in this case #1) and below Look at Eastings first – 18 Look at Northings Second What is 2? 3? 4? What if you have to find a point inside a grid?

Below – one square on the same grid • Step one – divide the square further into 10 ths • The grey square is located in the square 1844 • More accurately it is 7 tenths across and 8 tenths up within the grid square 1844 and therefore has the 6 -figure map reference 187448. • Try the red circle (starting with 1844) • 185443