Junius Henderson -- 4 augustus 1909

Rifle Gap State Park, Aug 4, 1909

Arose at 6:30. After breakfast Terry and I started down into the Gap on the SE side of creek. Between the first well defined sandstone ledge and the second we found Cardium speciosum, Mactra, Ostrea, Anchura, Lunatia and other gastropods in float rock. Immediately above the second ledge we found a fossiliferous stratum 2 or 3 ft. in thickness, dipping S angle 73¡, containing Anomia raeti-formis [?], Corbicula, Ostrea, and with no Cardium or gastropods. The first s.s. does not make a ridge on the W side of the gap. Above the next s.s. is a coal vein which has been worked somewhat on both sides of gap. This is overlaid by clay shales, then sandy shales. About 100 ft. above this is a series of burned s.s. and clays which I estimated to be 200 ft. thick, probably metamorphosed by burning of coal veins. This is overlaid by a massive s.s. like the Laramie, which in turn is overlaid by alternating s.s. etc. as below. I notice two more coal openings above this on W side of gap, the uppermost but little below the upper ridge making sandstone ledge. All along the sandy slope we found dead Oreohelix cooperi, but saw no live ones, though, for that matter, I did not look for them. Took one picture looking at the W side of the gap, down stream, another of the lower Mesa Verde on the W side from the E side. Another of the upper fossil outcrop on E side. Reached camp at 1:30 p.m.. Very hot forenoon. Afternoon I cleaned the Oreohelix from Newcastle, Colorado and found both species to contain young. Then at 4 p.m. Terry and I visited the very steep slope showing upper Mancos shales and lower Mesa Verde sandstones. In the lower Mesa Verde we found a thick stratum (about 8 inches) filled with fossils, including Baculites, Bryozoa, Serpula markmani, Anchura, et al., but no Cardium, Mactra, Callista or Ostrea. The three faunas we have found here are very distinct. In this last horizon we also found 2 specimens of Halymenites major and many plant stems, probably marine. Reached camp at 6:30, retired at 9:30


Junius Henderson (1865-1937): Field Notes.