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Confirming The Glacial Origins of Yosemite -- The First Continuous High-Resolution Map of the High Sierra Back Country
This map of the Glaciers of Yosemite distills decades of investigation by geologist–cartographer François E. Matthes.
Born in Amsterdam in 1874, Matthes spent part of his boyhood in the Alps, where he learned to read General Dufour’s hatchured military maps and developed a lifelong fascination with mountainous terrain. After training in technical drawing and surveying at MIT and working with the U.S. Coast and Geodetic Survey, he introduced new field tools to U.S. Geological Survey mapping, most notably a telescopic alidade that let him sketch accurate contour lines,. By the early 1900s he was assigned to Yosemite, determined to settle long-standing debates about how glaciers, rivers, and tectonics had sculpted the valley’s sheer walls.
Matthes approached mapping as “an interpretative and synthetic art,” believing that clean symbology could translate complex field evidence into an intelligible story. His glacier map overlays a 1 : 24 000 topographic base (100-foot contours) with a concise legend: white lobes flecked with blue crevasse marks for Tioga-age ice; blue arrows for flow direction; brown dot-rows for medial moraines; and a green line encircling older Tahoe and pre-Tahoe ice limits. These symbols do more than locate past glaciers—they animate them, showing how tributary tongues from the Lyell, Cathedral, and Clark Ranges merged, split, and ultimately carved Yosemite Valley, Tenaya Canyon, and Tuolumne Meadows. A small marginal note warning of an 85-foot datum error south of 38° N and west of 119° 30′ W reminds readers how quickly survey accuracy was evolving in Matthes’s era.
Earlier efforts to map the region's glaciers, including Wheeler’s 1870s reconnaissance, stop-and-start Army surveys, and the Sierra Club’s piecemeal valley sheets, had produced only fragmentary coverage. Matthes, working through two snow-shortened field seasons, produced the first continuous high-resolution map of the high Sierra back country. He then re-examined every polished bedrock surface, erratic, and moraine train to assign them confidently to specific glacial stages. In effect, the map functions as a time slice: by following the blue arrows and green outline, the reader can visualize successive ice advances and retreats over tens of thousands of years.
The plate offers a case study in how field observation, geomorphology, and cartographic design reinforce one another, illustrating how a single image can merge quantitative elevation data with qualitative geological interpretation. The map also provides a fascinating artifact of Matthes's work, hauling instruments into remote cirques, refining his hypotheses each evening by lantern light, and ultimately translating raw field notes into a clear, engaging map.
François Émile Matthes (March 16, 1874 – June 21, 1948) was a pioneering geologist, topographer, and an authority on glaciers and climate change.
Born in Amsterdam, the Netherlands, Matthes was introduced to the natural sciences early in life, influenced by his family's frequent travels in the Alps and his fascination with fossils and mountaineering. His upbringing was marked by a robust education across Europe, where he became fluent in multiple languages and developed a strong foundation in technical drawing and engineering. Matthes and his twin brother Gerard immigrated to the United States in 1891 to study civil engineering at the Massachusetts Institute of Technology (MIT). After graduating with honors in 1895, both brothers became naturalized U.S. citizens in 1896.
Matthes began his career with the United States Geological Survey (USGS) in 1896, initially as an instrument man and draftsman. Over the next several decades, Matthes played a significant role in mapping remote areas of the American West. He undertook extensive fieldwork across Wyoming, Montana, Arizona, and California, producing detailed topographic maps that later facilitated the establishment of national parks. His work in topography was distinguished by his meticulous field techniques and his insistence on integrating geological studies with mapping, a practice that enhanced the scientific value of his maps.
Matthes is best known for his contributions to the study of Yosemite Valley. Starting in 1905, he was tasked with resolving the long-standing debate between Josiah Whitney’s theory of block faulting and John Muir’s glacial hypothesis concerning the valley’s formation. Matthes’ research culminated in the 1930 publication Geologic History of the Yosemite Valley, which provided definitive evidence of the valley’s glacial origins. His work in Yosemite also introduced key glaciological concepts such as "nivation" and the identification of the "Little Ice Age," terms that remain central to modern geomorphology. Matthes’ contributions extended beyond research; he was a co-founder of the Association of American Geographers (AAG) and served as its president in 1933.
Throughout his career, Matthes balanced his scientific pursuits with public service, including leadership roles in Boy Scouts of America and participation in international geological associations. His extensive publications on geomorphology, glaciology, and topographic mapping continue to be referenced in geological studies. In recognition of his achievements, several geographic features, including Matthes Crest and Matthes Lake in Yosemite National Park, are named in his honor.
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