A number of collapsed structures are present in the Beaver Creek Watershed.
These structures range is size from 0.6 m (a few feet) to about 90 m (300
ft) in diameter. These features result from flowage of lava from underneath
an already frozen lava cover. The unsupported lava cover yields to weathering
and gravitational stress by collapsing shortly after freezing of the lava.
The largest of the collapse structures is the depression occupied by
Stoneman Lake. The Stoneman Lake structure is too large to be explained
by collapse into a lava flow cavern. The present crater floor is nearly
90 m (300 ft) below the rim and is underlain by lake beds at least 90
m (300 ft) thick indicating that the original lava roof has collapsed
more than 183 m (600 ft). This distance exceeds the total thickness of
lava believed to be present in this area. Possible explanations of this
structure are collapse into a magna chamber at greater depth or into fractures
or caverns in the underlying sedimentary rocks.
Stoneman Lake and its watershed, comprising less than 400 ha (1,000 ac),
forms a small interior basin that has no surface outlet.
McCabe, K.W. 1971. A geo-botanical study of Stoneman Lake, Wet Beaver
Creek experimental drainage basin, Coconino County, Arizona. MS Thesis,
Northern Arizona University, Flagstaff, Arizona.
Williams, J.A.; Anderson, T.C., Jr. 1967. Soil survey of Beaver Creek
area, Arizona. USDA Forest Service, Soil Conservation Service, and Arizona
Agriculture Experiment Station.