Geologic Map of the Maysville Quadrangle, Chaffee County, Colorado

of the range front area between the South Arkansas River and Sand Creek. A roughly five
sq mi area, including the bulk of Mount Shavano, in the northwest corner of the
quadrangle has very difficult access. Peripheral access to this area is provided by Forest
Service roads (240, 252 and 255) and the Colorado Trail. The main trail access into this
area is the Mount Shavano/Tabeguache Peak Trail, which uses the old trail in the south
fork of Squaw Creek. This trail provided access to the mines and prospects on the
patented claims on Mount Shavano and is currently maintained by the Forest Service.
The Maysville quadrangle includes several physiographic elements. Along the
western part of the Maysville quadrangle is the eastern flank of the Sawatch Range (fig.
1). The northwest corner of the quadrangle consists of the rugged southern and eastern
flanks of Mount Shavano. The southwest quadrant includes a series of east-northeasttrending,
bold ridges and valleys related to an area of Proterozoic rocks. The northeastern
and central part has low elevations and subdued topography related to the southwestern
part of the southern terminus of the Upper Arkansas Valley. The northeastern margin of
the quadrangle includes an area of low-lying badland topography related to the Dry
Union Formation. The central part of the quadrangle is a large, gently southeast sloping
area of Quaternary gravels that largely conceal the underlying Dry Union Formation. The
southeastern quadrant consists of a distinctive area of grass-covered, northeast-trending
sub-ridges formed in an uplifted area of the Dry Union Formation.
The maximum relief in the quadrangle is about 6,480 ft. Altitudes range from a
low of 7,750 ft along the South Arkansas River in the southeastern corner to a high of
14,229 ft at the summit of Mount Shavano in the northwest corner. Tabeguache Peak
(14,155 ft) occurs about 200 ft N-NW of the northwest corner of the quadrangle. Other
prominent landmarks in the region include Pahlone Peak (12,667 ft) and Mount Ouray
(13,971 ft), located 1.5 mi S-SW and 5.5 mi S-SE, respectively, of the southwest corner
of the quadrangle. The Continental Divide is located about 3 mi SW of the southwest
corner of the quadrangle.
The Arkansas River is the principal drainage for the Upper Arkansas Valley and
comes as close as about 2.2 mi to the east boundary of the quadrangle (fig. 1). The
southern part of the quadrangle is traversed by the South Arkansas River, the main
tributary draining the southern Sawatch Range in the Monarch Pass area. The North Fork
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