The Jurassic in this region is complicated. The rock units have been correlated and recorrelated many times by many researchers. An important contribution that was largely (but not completely) accepted by later workers was done by Pipiringos and O'Sullivan (1978).Their work (which also extends well beyond the area in these webpages), is based on 5 regional Jurassic unconformities:

J5 Generally occurs at the base of the Morrison Formation J4 Occurs mostly in Wyoming, South Dakota, and others areas to the far norht of the Four Corners J3 Found under the Curtis Formation in the San Rafael Swell, and potentially in northern Arizona J2 A widespread unconformity marked by chert pebbles. Its identifcation clarifies the stratigraphy confusion in New Mexico with the Wingate and Entrada Sandstones. J1 Occurs in Wyoming (ignored in these webpages) J0 The unconformity at the base of the Jurassic section, carved into the Triassic section

Pipiringos, G.N., and O’Sullivan, R.B., 1978, Principal unconformities in Triassic and Jurassic rocks, Western Interior United States – a preliminary survey: U.S. Geological Survey Professional Paper 1035-A, p. A1-A29.