20 Tuscaloosa Formation [218 



history which has interested me chiefly in connection with the 

 interpretation, in terms of geologic history, of the extensive 

 fossil floras that have been found in the earliest Upper Creta- 

 ceous or Tuscaloosa formation of this region. 



The Tuscaloosa formation in the area around Tuscaloosa, 

 Alabama, and for some distance to the northwest consists of 

 about 1,000 feet of predominantly sandy materials which 

 give the country its present topography. These sands are 

 usually light in color, cross-bedded and micaceous occasion- 

 ally there are traces of glauconitic layers. There are heavy 

 beds of gravel made up of well rounded quartz and sub- 

 angular chert pebbles in about equal proportions in places, 

 especially toward the landward margin of the deposits and 

 northward along the strike. In disconnected and interbedded 

 lenses there is a considerable amount of argillaceous material 

 at times massive or heavy bedded, but generally laminated. 

 Thin seams of lignite are present at various levels but these 

 are generally only a few inches or less in thickness. The clays 

 are often oxidized and mottled in color but they are as fre- 

 quently very carbonaceous and dark in color. In some sec- 

 tions, as in the Big Gully section southwest of the town of 

 Tuscaloosa, there are layers filled with prostrate logs of trees 

 of large size. Pyrite and ferruginous oxide, forming locally 

 indurated sandstones and gravels are generally distributed, 

 and finely disseminated gypsum crystals are very common. 



No fossils other than the remains of land plants have been 

 found in the Tuscaloosa deposits. Usually the plant remains 

 are much macerated and broken by water transportation and 

 deposited in films of broken fragments in the laminated beds. 

 Drift logs are common and these occasionally brought down 

 cobbles imbedded in their roots (statement based on speci- 

 mens collected in lignitized tree roots). There appear to 

 have been areas of quiet waters at certain localities where the 

 leaf remains in the clays are abundant and in a state of 

 preservation indicating that they grew in the immediate 

 vicinity. 



The outcrop of the Tuscaloosa formation, as shown in the 



