Stratigraphy and origin of the Chinle Formation and related Upper Triassic strata in the Colorado Plateau region, with a section on sedimentary petrology and a section on conglomerate studies

Paleogene rim gravel of Arizona: Age and significance of the Music Mountain Formation

“…In addition, the presence of very large diameter petrifi ed logs with no evidence of fl uvial abrasion in Prices' (1950) Type B gravel indicates that such fossil materials probably represent the indigenous fl ora, similar to the large petrifi ed logs with delicate bark structures preserved (as described in Young, 1999) and photographed on the Hualapai Plateau (Young, 2011, fi g. 8 therein). Albee's (1956) detailed study of pebble types in the Shinarump Conglomerate reinforces the fi ndings of Stewart et al (1972) in that Albee's mean pebble size is slightly <2.5 cm. The largest quartzite pebble noted in the combined Shina rump studies was 12.7 cm.…”

“…With the benefi t of hindsight, Price's (1950) Type B gravels probably should be assigned to a category of reworked Laramide lag gravels, originally deposited prior to the initiation of widespread Miocene volcanism. Some contribution of Shinarump Conglomerate pebbles to exotic rim gravels is possible on the southern Colorado Plateau; however, Shinarump Conglomerate quartzite clasts throughout northern Arizona are considerably smaller than typical rim gravel quartzite clasts, as documented by Stewart et al (1972). In addition, the presence of very large diameter petrifi ed logs with no evidence of fl uvial abrasion in Prices' (1950) Type B gravel indicates that such fossil materials probably represent the indigenous fl ora, similar to the large petrifi ed logs with delicate bark structures preserved (as described in Young, 1999) and photographed on the Hualapai Plateau (Young, 2011, fi g. 8 therein).…”

A new phytosaur (Archosauriformes, Phytosauria) from the Lot’s Wife beds (Sonsela Member) within the Chinle Formation (Upper Triassic) of Petrified Forest National Park, Arizona

“…The Chinle Formation of Arizona is one of the richest formations for phytosaurs (Camp, 1930;Parker and Irmis, 2006;Stocker, 2008Stocker, , 2010. The Chinle Formation (sensu Woody, 2003Woody, , 2006Martz and Parker, 2010) represents an extensive deposit of fluvial, lacustrine, and floodplain sediments that extend throughout the American Southwest (Stewart et al, 1972;Dubiel, 1994). In Arizona, the Chinle Formation traditionally consists of the Shinarump, Mesa Redondo, Blue Mesa, Sonsela, Petrified Forest, Owl Rock, and Rock Point members (Woody, 2006), of which the Blue Mesa through the Owl Rock members are present in Petrified Forest National Park (Fig.…”

A new hump-backed ginglymodian fish (Neopterygii, Semionotiformes) from the Upper Triassic Chinle Formation of southeastern Utah

“…The Triassic habitat of the Chinle Formation in Lisbon Valley has been interpreted by previous studies (e.g., Stewart et al, 1972;Blakey, 1989) as a freshwater system with a perennial, monsoonal climate (Dubiel, 1987), which transitioned from humid to increasingly arid over time (Blakey and Gubitosa, 1983). The fossil fish-bearing layers of the Church Rock Member (Chinle Formation, Lisbon Valley) are in isolated channel deposits of fine-grained sandstones and mudstones.…”