Mapping And Imagination In The Great Basin: A Cartographic History

5. Demystifying Terra Incognita: 1825–1850

The early-to-mid-nineteenth century marked a time when cartographers scrambled to try to depict the topography and hydrology of the West accurately . Despite their efforts,however,considerable speculation was common, and errors frequent. Consider Anthony Finley’s interesting but conflicted Map of Western America (fig. 5.1). Produced in 1826, it shows a fragmented Sierra Nevada breached by numerous rivers. Finley’s disjointed mountain range obediently parts to permit the westward-flowing rivers of empire to reach the Pacific in California.This map reveals a conundrum that would soon be resolved, and that resolution reminds us that cartography is a complex drama featuring many actors. Some of these actors were explorers whose experiences confronted widely held beliefs, long-cherished cartographic traditions, and deeply rooted cartographic icons. Consider, too, the case of those who longed to make sense out of the eastern portion of the Great Basin.The key here would be determining the shape of what we today call the Great Salt Lake, which was circumnavigated by a party of American explorers under General Ashley as early as 1826. Like other observers, they were well aware of the lake’s hypersalinity. To us with the advantage of hindsight, the salinity of the Great Salt Lake seems like a simple, definitive clue to the region’s aridity. After all, we now know that evaporation exceeds precipitation, and that this remnant of an inland sea (Lake Bonneville) increased in salinity as it shrank in size. But the very factor of its salinity worked against explorers’ understanding its real charac69 Demystifying Terra Incognita 1825–1850 5 70 mapping and imagination in the great basin ter. When they first encountered the Great Salt Lake, they were amazed by its “bitterness,” but that only seemed to prove that it was an arm of the sea, for what else could a body of salt water this large be? Beliefs like this die hard, even in the face of evidence. In 1826, Niles’ Register reported that Ashley’s men had coasted the perimeter of the lake. Evidently, however, the explorers were unable to comprehend a lake with no drainage to the sea. So figure 5.1. Alexander Finley, North America (1830). Courtesy Special Collections Division, University of Texas at Arlington Libraries demystifiying TERRA INCOGNITA 71 strong was their faith that they believed their assumptions rather than what they had actually experienced: The reporter noted that although“[t]hey did not exactly ascertain its outlet[,]” they felt certain that they must have “passed a place where they supposed it must have been.”1 These explorers were deep in the wild heart of interior Northern Mexdetail of figure 5.1 72 mapping and imagination in the great basin ico at the time. Like others before them, they were seeking the Pacific unaware of the Sierra Nevada’s stranglehold on rivers. Throughout the 1820s and early 1830s, the interior of Alta California, including much of today’s Nevada and Utah, would remain largely unknown, even though an established trade route now skirted its southern edge. But the region’s isolated status actually invited new interest by others wishing to cross it as they sought the Pacific ports and trade with the Orient.These Anglo-Americans relied on maps from the early 1800s that tended to simplify the topography and grossly distort distances. Still revealing influences of the Jeffersonian-era tendency to misrepresent and misplace the
ocky Mountains, these maps severely compress the distance between Pike’s Peak and the Pacific Coast. For example, although the distance from Pike’s Peak to the Pacific is really 1,006 miles,
obinson’s (and later) maps show it to be but 660 miles. Consider this compression a metaphor: It effectively squeezed the IntermountainWest out of the public’s consciousness. The promoters of western railroads to the Pacific Ocean in the 1820s and 1830s were especially prone to downplay the great distances and formidable topography that would be encountered here.2 This oversight by mapmakers was understandable for two reasons. First, relatively little information was available. Second, few obstacles and short distances further encouraged belief in technology’s ability to span the West. The mapmakers’ combined ignorance and wishful thinking helped support their advocacy of a railroad line across the region fully four decades before the transcontinental railroad ultimately crossed it in 1869. Ignorance was inadvertently assisted by the cartographers who perpetuated errors from previous maps. Such geographic oversights were...