Cartography 101

A few terms you should know Field – A particular area where similar quantities can be measured at all points or locations Isolines – Connect the point of equal value on a field map Examples – Isotherm (temp), Isobars (pressure), contour lines (elevation)

Just one more…. Isosurface – A surface where all the points have the same measured value Can anyone think of what “iso” means? Yup, it means equal or the same!

Topographic Maps Also referred to as Contour Maps Shows elevations and the shape of landscape features Contours are separated by defined intervals called contour intervals - Contour intervals are uniform throughout the map Contour Interval = Δ in height between two adjacent contour lines.

What do Contour Lines Tell Us? From the shape of the contours you can recognize land features such as hills, mountains, depressions, cliffs, etc. When contours are far apart the slope of the ground is fairly level. When contours are close together the slope of the ground is fairly steep.

Other Topographic Map Features Every topographic map will tell you which direction is north. Key or Legend Printed on the map to give other valuable information like rivers, roads, structures, paths, vegetation, etc.

What is this thing called Gradient? Gradient – The change in field value per unit distance What that actually means: How much the field value (temperature, pressure or elevation) changes over a measured distance. Cover of ESRT - Formula for gradient Gradient = (change in field value) / (distance)

Creating a Profile A profile is the side view of a topographic map. Profiles are used to obtain a “better view” one in which you can see the vertical changes in the topography (landscape) Steps to creating a Profile 1) Place a separate piece of paper along the line which you want to profile 2) Mark on the paper every place a contour touches the paper and label it’s elevation value 3) Put the strip of paper along the x-axis of a graph and project the points upward. 4) Connect the dots and create the profile.