Page:The Journal of geology (IA journalofgeology21894univers).pdf/265

resented than in the following figure copied from Professor Newton's report:^[1]

At that date the opinion widely prevailed that there was no Lower Cretaceous in North America. The Shasta, Kootanie, and Comanche groups were unknown, the Potomac of Virginia was supposed to be "Upper Oolite," and the Iron Ore Clays of Maryland and Plastic Clays of New Jersey were classed as Wealden and referred to the Jurassic. Meek and Hayden had been unable to find any Cretaceous deposits lower than No. 1 of

Fig. 1.Ideal section across Red Valley on Amphibious Creek.

1. Carboniferous.
2. Red sandstones and clay (Red Beds).
3. Purple limestone (Red Beds).
4. Red clay with gypsum (Red Beds).
5. Jura.
6. Cretaceous sandstone capping the foot-hills.

their famous section, and this was believed to be the oldest Cretaceous deposited on this continent, which was supposed in some way to have been out of water during the entire period that separated this from the Jurassic.

My attention was first attracted to the Black Hills by a letter received at the Smithsonian Institution in February, 1893, from a resident of Hot Springs, South Dakota, inclosing photographs of certain petrifactions found in that vicinity which he said had been called "Cycads." The letter and photographs were referred to me on the presumption that these objects were of vegetable origin. I at once perceived that they were fossil cycadean trunks closely resembling those collected by Tyson in 1860 in the Iron Ore Clays of Maryland and named by Professor Fontaine Tysonia Marylandica, and, therefore, also similar to the forms found by Mantell and others in the early part of the cen-