LANCE FLORA OF EASTERN WYOMING 95 



U. S. Geol. Survey Locality 1463. Ravine IJ miles southwest of U-L Ranch (apparently 

 same as Locality P3856 of the present report) : 



FiUcites knowltoni Salvinia? sp. 



Nymphaeites browni Trapa? microphylla 



Phyllites trifoliatus 



U. S. Geol. Survey Locality 1464- East bank of Lance Creek, just below U-L Ranch (same 

 as Locahty P3857 of present report) : 

 Myrtophyllum torreyi 



U. S. Geol. Survey Locality 1469. East bank of Lance Creek, 2 miles above the mouth of 

 Lightning Creek: 



Salix lancensis 



U. S. Geol. Survey Locality 1479. Near Buck Creek corrals, Converse County, Wyoming. 

 CoIIected by T. W. Stanton, July 17, 1896: 

 Carpites ulmiformis 

 U. S. Geol. Survey Locality 1485. East side of Lance Creek, 1 mile north of the Pierre shale: 

 Nelumbo tenuifolia 



U. S. Geol. Survey Locality. No number given; Lance formation ("Ceratops beds"), Lance 

 Creek, Converse County, Wyoming. Collected by J. B. Hatcher, June 1881: 



Ficus? ceratops 



Fort Union Group 



The deposits above the Lance formation have been generally referred to the 

 Fort Union "formation" on the basis of stratigraphic position, hthology, absence of 

 dinosaurs, and the presence of a typical Lower Eocene (Paleocene) flora.^ The 

 contact between the typical Lance formation and the lowest unit of the Fort Union 

 group has been discussed under the Lance formation. This contact is traceable 

 northward into the Gillette coal field region, where it coincides, so far as I can deter- 

 mine, with the contact between the Hell Creek and TuIIock formations.- The Tul- 

 lock formation was regarded by Dobbin and Barnett, as elsewhere by others, as the 

 upper member of the Lance formation. In the Gillette coal field, as well as at its 

 type locality and elsewhere, the TuIIock formation is now known to contain plant 

 remains of typical Paleocene Fort Union aspect.^ This conclusion is substantiated 

 by the southward extension of the Tullock of the Gillette coal field into the Fort 

 Union beds above the top of the Lance formation, as defined, in the Lance Creek 

 area. It is evident, therefore, that the lower unit of the Fort Union group of the 

 Lance Creek area is equivalent to the Tullock formation, which is traceable from 

 its type locality in eastern Montana into the area of the Gillette coal field.* 



The lithologic characters of the "TuIIock" formation in the Lance Creek area 

 are in distinct contrast with those of the type Lance. Sandstones are thin, yel- 

 lowish, fine-grained, and fairly hard. They are more persistent than the sandstones 

 of the Lance formation and form a fairly prominent succession of low scarps which 

 stand above the rolling, subdued lowlands developed on the Lance formation. The 



■ Stanton T. W., and Knowlton, F. H., op. cit., 134, 1897. Dorf, E., BuU. Geol. Soc. Amer., vol. 51, 216, 232, 1940. 



2 Dobbin, C. E., and Barnett, V. H., U. S. Geol. Surv. Bull. 796-A, 8, 9, 1927. 



' Dorf, E., op. cit., 223-232, 1940. 



• Dobbin, C. E., and Barnett, V. H., op. cit., 8, 1927. 



