In the Indio Mountains of West Texas, the clastic early rift fill is the 1,500 m thick Yucca Formation. The restricted facies belts associated with the narrow sea provides a stratigraphic correlation of allows definition of 6 stratigraphic intervals. The lowest two form an alluvial fan complex. Units 3 through 5 were deposited in a coastal fluvial system and comprise a series of braided and meandering streams, floodplains and associated deltaic deposits. The top of unit 5 records an abrupt transgression that forms the primary stratigraphic marker within this interval and allows correlation between thrust sheets.
Along with the change from fluvial, to interstratified fluvial and marine strata was a compression of the lateral facies changes. The upper marine influenced intervals change from almost entirely fluvial to dominantly marine within three kilometers. This abrupt change, both stratigraphically and creates a piercing point that allows correlation of the direction and magnitude of thrusting as well as expansion of section into the deeper central Chihuahua trough.