Fist off the history of topography was initiated from a man named James Wesley Powell, a geologist in the 80's, who convinced congress to gather a team in developing topographic maps. Not only did his efforts benefit for resources and hydrology of the western landscape but it benefited outdoor enthusiasts to navigate more safely.
The maps scale will let us know how much detail the map contains. The miles and fractions of the measuring will tell us what each line represents to calculate the distance. Usually the smaller the scale the more details. The legend on the map tells us symbols, colors and different representations of the lines from rivers to roads or campgrounds. The legend also includes data to read and navigate on the map itself. The contours on our map to the left tell me where the landscape elevation changes and how big the change is on land. Depending on where I choose to travel around Zion or in Zion I will closely pay attention to those numbers indicating how steep or gradual the landmass will change to.
A very beneficial feature of topographic maps are the magnetic declination. The angle between magnetic north and true north can be found using the legend on the map keeping the hiker on the correct course. This is especially important considering when hiking out in the mountains there is no signal to help guide the explorers out there. Although finding trails can be fun it can also be very dangerous. A compass is needed to adjust to the declination angle on the maps legend. An example, if east of Mississippi River adjust the declination angle in westward direction. If west of the river adjust in an eastward direction.
Each contour is a line of equal elevation so the contours never cross. The lines define the general shape of the terrain. Finding the elevation on a topographic map starts with finding the nearest labeled line and counting the number of lines above and below it. In the photo the closest line is 9250 and the next number is 10,500. Those subtracted is 1,250 meaning the contour interval of the map. The more close the lines are the steeper the slope. In the photo the lines seem pretty steep so the possibility of a mountain in this area is great.
https://www.rei.com/learn/expert-advice/topo-maps-how-to-use.html
https://www.geomag.nrcan.gc.ca/mag_fld/magdec-en.php