S P Crater is a cinder cone

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

in the

San Francisco volcanic field The San Francisco volcanic field is an area of volcanoes in northern Arizona, north of Flagstaff, US. The field covers 1,800 square miles (4,700 km²) of the southern boundary of the Colorado Plateau. The field contains 600 volcanoes rang ...

, north of Flagstaff, Arizona, United States. It is surrounded by several other cinder cones which are older and more eroded. It is a striking feature on the local landscape, with a well-defined lava flow that extends for to the north. American astronauts use the crater to train for moonwalking.

Name

The naming of the mountain is a bit of lore from the Old West. S P Crater can be climbed, and the lava flow can be viewed from the crater rim. C. J. Babbit, an 1880s rancher and early landowner of the mountain, expressed his opinion that the mountain resembled a spilled

chamber pot A chamber pot is a portable toilet, meant for nocturnal use in the bedroom. It was common in many cultures before the advent of indoor plumbing and flushing toilets. Names and etymology "Chamber" is an older term for bedroom. The chamber pot ...

(or Shit Pot, "SP"), and locally this became the accepted name. When viewed from certain angles on the ground, the combination of the smooth round shape of the cone, the dark lava spatter on the rim, and the long dark lava flow extruding from the base may resemble human waste. Mapmakers refused to spell out the full name, and the mountain has been shown on maps and other literature with the abbreviated name.

Geology

S P Crater is an high cinder cone of

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Amer ...

. The cone is capped by an agglutinate rim that helps to protect its structure. A lava flow extends to the north of the cone for about and originated from the same vent. Some scientists consider the lava flow to have slightly predated the cinder cone because of geochemical data that suggests the flow is more silica rich than the cinders and based on the observation that the cone overlaps the lava flow and shows no sign of

deformation Deformation can refer to: * Deformation (engineering), changes in an object's shape or form due to the application of a force or forces. ** Deformation (physics), such changes considered and analyzed as displacements of continuum bodies. * Defor ...

. However, there is some debate about the relationship between the cone and flow as it is not uncommon to form cinder cones during the early phase of an eruption as a magma degasses, and then to have lava push through the side of a cone during a late phase of eruption. K–Ar dates on the lava are about 70 ka, but are considered unreliable because of excess

argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as ...

and the un-weathered young appearance of the cone.

References

External links

* (photo gallery) * ( hike to the top ) * {{Mountains of Arizona Mountains of Arizona Cinder cones of the United States Landforms of Coconino County, Arizona Volcanoes of Arizona Mountains of Coconino County, Arizona