McKee (1949)
McKees research, which integrated faunal and
stratal correlations, revealed that the Cambrian formations in the
Grand Canyon were time-transgressive.
Tapeats/Bright Angel Contact in SW part of
Canyon was Early Cambrian in age, the same lithostratigraphic
transition to NE was Middle Cambrian in age & equivalent to Bright Angle/Mauv
contact to west.