Surprise Canyon Formation

Surprise Canyon Formation Stratigraphic range: Upper Mississippian, Lower Pennsylvanian, 325–316 Ma PreЄ Є O S D C P T J K Pg N
Pattie Butte-(Newton Butte), sitting on 'redbeds' of Supai Group The ridgeline, north sits on Redwall Limestone 'platform'–(2-places, photo-bottom-left, top of red Redwall cliff), and topped by 2nd-platform of Surprise Canyon Formation. Note: 3-prominences: center, "Unnamed"; Newton Butte-(off-photo, right); Pattie Butte, center, bottom-left, (on platform, north terminus).
Type	Geological formation
Underlies	Watahomigi Formation, (1st member)-Supai Group 'redbeds'
Overlies	Redwall Limestone
Thickness	400 feet (122 m) max (50-400 ft typical)
Lithology
Primary	conglomerate, sandstone, limestone
Location
Region	Colorado Plateau (southwest areas)
Extent	Grand Canyon

The Late Mississippian-Early Pennsylvanian Surprise Canyon Formation is a conglomerate, sandstone, limestone and dark purple siltstone type formation, occurring as 'channel fill'. The Surprise Canyon Formation was deposited upon a mostly horizontal, much eroded Redwall Limestone surface, the Redwall originally deposited as marine-(oceanic) limestone, (400 to 700 ft thick); when the Surprise Canyon Formation was being deposited, the Redwall Limestone surface existed under karst topography conditions, in a "warm, and humid" (paleo)-environment. The karst topography created "sinks, caves, and underground channels", and created "deep ravines and stream valleys developed as caverns collapsed". Some valleys probably filled with " 'clayey red-orange soil' similar to that known in the Tropics today." Below the Redwall surface, solution-cavern deposits of the Surprise Canyon, have a Redwall Limestone geologic layer, now expressed above them.

The Surprise Canyon Formation is found extensively in regions below Grand Canyon Village, Arizona, South Rim, regions northwest, north, and northeast. It is discontinuous, but is found in geologic sequences below the South Rim, and its various landforms, and also especially at the Inner Gorge in specific landforms that have cliffs, and upper surface platforms of the Redwall Limestone. Example landforms near Grand Canyon Village, are Pattie Butte-(Newton Butte), Tower of Set, (due west of Isis Temple), and Brahma Temple's southern Redwall Limestone points, Johnson and Sturdevant Points, due east of Isis Temple.

Fossils of plant material, marine shells, where some fossils may have been 'derived fossils' from the Redwall Limestone, are found in the formation; also fossil logs, showing the erosion, or valley and canyon topographies and the erosional forces of the time period.

Besides the easily recognized locations of the Surprise Canyon Formation on the Redwall Limestone platforms, it is found in more vertical sequences where the lowest Supai Group member, the Watahomigi Formation, major sub-unit 1 of 4, transitions, and sits upon the Surprise Canyon, upon the Redwall Limestone. As stated, the Surprise Canyon in the Grand Canyon Village region is discontinuous, but occurs in all sub-sections, further explaining a many-channeled paleo-surface of the eroding Redwall Limestone. The supplementing, and later hypothesis is that marine conditions, to the west of the proto-North American continent, had created an estuarine region, with accumulations of the continental erosion; with apparent uniform thicknesses of the Surprise Canyon, as opposed to highly variable thickness, near sea-level conditions, and probably lack of high terrains on the eroding Redwall surface, and all factors leading to the thin, discontinuous accumulations, but thin lenses, and regionally extensive in the estuary (sea level) region.