Since my pre-teen years, I have been fascinated by maps. I can still recall how that first geography text, with its simplified images of the Nile and Amazon, instilled a sense of adventure in my soul. At about the same age, I began to draw maps of our neighborhood forest, with its trails, cliffs and creeks, giving me an early appreciation for regional topography. In later years, when I set out for nature preserves and wilderness areas, I graduated to the use of topographic maps and, in the production of our outdoor guides, took special delight in sketching maps for each location.
Those of us who appreciate the varied landscapes of this planet know that a map of rivers and streams provides the best clue to a region's topography. A dendritic pattern suggests a dissected plateau while parallel, meandering streams indicate a flat plain. Creeks that end in ephemeral lakes descend the walls of a basin while those that abruptly disappear suggest karst topography with sinkholes, caves and underground streams. Finally, mirrored, branching networks flank a divide, revealing the presence of a ridge or mountain range. Always seeking low ground, streams guide our eyes across the landscape, from lofty summits to the vast, level sea.