Geologic Map of the Maysville Quadrangle, Chaffee County, Colorado

Fault surface rupture during a large earthquake might instantaneously rupture the
ground surface and uplift the upthrown side of the fault by 5-8 ft. This movement might
displace any structures or facilities sited across the fault trace (typically located beneath
the center of the mapped fault scarps), such as roads, canals, pipelines, buried utilities, or
houses or barns. Fortunately, the Shavano fault traces lie in a remote and undeveloped
area with difficult access. Only in the North Fork do traces of the Shavano fault cross any
infrastructure, such as the Angel of Shavano Campground.
ABANDONED MINED LANDS
Collapse of abandoned mine shafts and adits, many of which may be covered by
thin surficial material, pose a potential hazard. A number of abandoned mines are present
in the Maysville quadrangle and are mostly clustered in the Proterozoic terrane in the
southwest quadrant. In addition, some abandoned mines are located along the Shavano
fault zone along the range front in the northwest quadrant; a cluster of seven placer mine
cuts is present in Droney Gulch at the east edge of the quadrangle. A total of 44 mine
adits, 12 mine shafts, and 14 cat cuts/trenches were located during this study. In addition,
about 100 prospect pits were found and they are commonly clustered in the same areas as
the significant mines. Mine and prospect locations are shown on plate 1 and UTM
coordinates are given in appendix 1. Prospect pits are generally from about 1 to 6 ft deep
with small waste piles; pits over about 10 ft deep with moderate to large waste dumps are
considered to be caved shafts.
None of the abandoned mines have been officially sealed, and most have
collapsed or caved by themselves over the years. A few of the larger mines have adits and
shafts that are open or partly caved and represent potential hazards to humans and
animals. The most dangerous hazards are two open shafts located at 396300E, 4265404N
and 392536E, 4265221N. In addition, caved or slumped shafts that may still present
hazards are located at 394411E, 4272693N; 392133E, 4274205N; 395635E, 4263036N;
393899E, 4265778N; and 394692E, 4265610N. Open adits or partly caved adits were
found at 395684E, 4262799N; 391634E, 4263994N; 391299E, 4263069N; and 395540E,
180