494 STEVENSON— THE FORMATION OF COAL BEDS, l^'ov. i, 



He states that 7 smaller but similar examples were found in 

 excavations for a street in Bradford. 



Grand'Eury and Goeppert have described many occurrences 

 of in situ trees ; and the former, in his memoir before the Geological 

 Congress at Paris, gave figures and descriptions of Calamites with 

 roots from the joints similar to those found by Sorby. Barrois^- 

 has reviewed the conditions in a keenly analytical memoir, referring 

 especially to conditions in the Nord basin. His discussion will 

 find place in another connection ; it suffices here to note that he 

 has found erect trees only in deposits which have been laid down 

 in shallow water ; they are wholly absent from deposits laid down 

 in water deep enough to float the trees. 



Not a few writers insist that occurrences of this sort can be 

 explained readily by supposing them to be due to landslides or 

 deluge-like floods. It might suffice to say with Goeppert that the 

 explanation might answer if the instances were few, but that it does 

 not answer because the number of erect trees is so great. But the 

 proposed explanation is wholly unacceptable because the conditions 

 observed do not suggest either landslides or terrific floods. 



The White Mountains of New Hampshire have long been cele- 

 brated for the extent of landslides. One is typical of all. Perkins*^ 

 described that which took place in the southern part of those moun- 

 tains after a prolonged heavy rain in October, 1869. The light- 

 colored streak marking its path was visible at a distance of 50 miles. 

 The whole mountain had been covered with a dense growth of 

 spruce. The slide began at 40 rods below the summit, 4,200 feet 

 above tide. It was barely one rod wide at the top and increased 

 little in the first 50 rods, where the slope is between 50 and 60 

 degrees; but, in the next 100 rods, the width increased rapidly to 

 25 and 30 rods at 130 rods from the beginning; thence it decreased 

 to 17 at 166 rods. The whole length is nearly 240 rods and the 

 outline is fusiform. Three miles below the termination of the 



*' C. Barrois, " La repartition des arbres debout dans le terrain houiller de 

 Lens et de Lievan," Ann. Soc. Geol. du Nord., Vol. XL., pp. 187-196. 



^.G. H. Perkins, "Notice of a Recent Landslide on Mount Passacono- 

 way," Anter. Joiirn. Sci., II., Vol. XLIX., 1870, pp. 158-161. 



