Named as the lower member of the Morrison formation for exposures on a small mesa east of Chaco Canyon road about 5 mi north of Chavez Siding on the Atchison, Topeka, and Santa Fe Railroad. Type section measured in sec 9, T14N, R13W, south of Mt. Powell, west side Thoreau quad, McKinley Co, NM in the San Juan basin. Resembles the Recapture shale member of the Morrison. Consists of alternating, variegated, greenish siltstone; purplish to reddish sandy mudstone; and white to buff, coarse-grained conglomeratic sandstone. Sandstone beds are 3-6 ft thick; siltstone beds are 1-3 ft thick; mudstone beds are 3 in to 6 ft thick. Variegated red, purple, and green mudstone nearly 15 ft thick occurs near top. Is 160 ft thick at type. Is nearly 200 ft thick at east boundary of quad. Mapped (geologic map) along north part of quad from the west side to about 1 mi west of the east side of the quad. Overlies Thoreau formation (new), upper formation of San Rafael group. Underlies Prewitt sandstone member (new) of Morrison. Columnar section. Jurassic age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Not used. Shown on a correlation chart as used by Smith (1954) and as equivalent to the Recapture Member of the Morrison Formation. Term Recapture used as basal member of Morrison in map area in preference to Chavez.

Source: GNU records (USGS DDS-6; Denver GNULEX).