I9II-] STEVEXSOX— FORMATION OF COAL BEDS. 633 



latest Cretaceous in the United States is mostly of freshwater origin 

 and it contains many coal beds ; but there is no positive evidence that 

 buried forests exist. Long ago, the writer saw, in New Mexico, 

 great numbers of stumps and trunks in a sandstone, apparently of 

 this age, and the same deposit has been mentioned by others ; but 

 there is no evidence on record to show that the stumps are i)i situ. 

 Lyell was convinced that he saw vertical stems of Equisetites in 

 place at a locality in the Triassic field near Richmond, in Virginia, 

 but his observations are not sufficiently in detail to justify one in 

 accepting them as evidence. It has been suggested that slender 

 stems such as those of Equisetnin or Calamitcs could not stand, 

 while a sandstone accumulated around them ; but the suggestion is 

 without basis. The writer has seen slender canes on the Gulf shore 

 of the [Mississippi delta, which had been killed many years before by 

 an invasion of salt water ; but they were still erect, though sediment 

 had accumulated around them to the thickness of several feet. 



The " dirt bed " of the isle of Portland, belonging to the Upper 

 Jurassic, was described long ago by Mantell.^"" The uppermost 

 Oolite stratum is a layer, one foot thick, of very dark friable loam, 

 which seems to have been a bed of vegetable mould. It contains a 

 large proportion of earthy lignite and also, like the modern soil of 

 the island, waterworn pebbles and stones. This is the " dirt bed " 

 of the quarrymen and upon it are branches and stems of conifers 

 and plants allied to Cycas and Zamia. Many of the trees and plants 

 stand erect as if petrified while growing undisturbed in their native 

 forests. Their roots extend into the " dirt bed " and their trunks 

 into the superincumbent limestone. At the time of Mantell's visit, 

 a large area had been exposed by stripping : 



" Some of the trunks were surrounded by a conical mound of cal- 

 careous earth, which had evidently, when in the state of mud, accumulated 

 around the stems and roots. The upright trunks were in general a few 

 feet apart and but 3 or 4 feet high ; they were broken or splintered at the 

 top, as if the trees had been snapped or wrenched off at a short distance 

 from the ground. Some were 2 feet in diameter, and the united fragments 

 of the prostrate trunks indicated a total length of between 30 and 40 feet. 

 In many examples, portions of branches remained attached to the stems." 



^^' G. A. Mantell, "Geological Excursions Around the Isle of Wight," 3d 

 Ed., London, 1854, pp. 287, 288. 



231 



