S P Crater is a

cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

in the San Francisco volcanic field, north of

Flagstaff, Arizona Flagstaff ( ), known locally as Flag, is the county seat of Coconino County, Arizona, in the southwestern United States. As of the 2020 United States census, the city's population was 76,831. Flagstaff is the principal city of the Coconino Cou ...

, 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

of basaltic andesite. The cone is capped by an

agglomerate Agglomerate (from the Latin ''agglomerare'' meaning "to form into a ball") is a coarse accumulation of large blocks of volcanic material that contains at least 75% bombs. Volcanic bombs differ from volcanic blocks in that their shape records flui ...

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. 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; it has 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 abu ...

and the un-weathered young appearance of the cone. More recent optically stimulated luminescence age dating on single-grain

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

xenocrysts from basalt flows at S P Crater has yielded more reliable ages of and for the older flow, and for the younger flow, together suggesting a generalized date of ~– that is more concordant with its youthful geomorphic character.

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 Holocene cinder cones