The Schnebly formation is by far the most prominent layer of the Sedona Red Rocks because of the presence of hematite or iron-oxide which rusts and stains the surrounding sandstone a red color (Arizona Ruins). The Schnebly Hill Sandstone formation is made up of three sections; the Bell Rock member, the Fort Apache member, and the Sycamore Pass member (Abbot and Cook, pg.177). This layer is separated from the Hermit formation by an unconformity that results in a gap of less than one million years. (United States Department of Agriculture). Of the sections of the Schnebly formation, the Bell Rock member, happened to be the most of a puzzle for geologist. The sandstone of this section was deposited in flat beds suggesting tidal waves were responsible for its deposition; however, the grains of sand themselves were very rounded suggesting that their deposition was the result of wind. To explain this, geologists stated that the sand of the Bell Rock Member was blown in from the north but the return of the sea almost 277 million years ago resulted in the presence of unusually flat beds (Abbot and Cook, pg. 183-185).
The Ft. Apache member of the Schnebly Hill Formation consists of limestone, siltstone, and dolomite, which is consistent with the discovery of the return of the Pedregosa Sea. Throughout most of Sedona, this layer is only 10-20 feet thick; however, near Fort Apache the limestone-rich layer is over 100 feet thick, leading geologists to confirm that the sea came in from the southeast. The Sycamore Pass member that covers the Ft. Apache was formed by the Sand Dunes that took the place of the Sea 270 million years ago (United States Department of Agriculture).
The Ft. Apache member of the Schnebly Hill Formation consists of limestone, siltstone, and dolomite, which is consistent with the discovery of the return of the Pedregosa Sea. Throughout most of Sedona, this layer is only 10-20 feet thick; however, near Fort Apache the limestone-rich layer is over 100 feet thick, leading geologists to confirm that the sea came in from the southeast. The Sycamore Pass member that covers the Ft. Apache was formed by the Sand Dunes that took the place of the Sea 270 million years ago (United States Department of Agriculture).