Mr. 'hoGG on the Wolds of Lincolnshire. 397 



Every variety of this stratum agrees in the two following proper-" 

 ties, the presence of calcareous matter, which is manifested by a. 

 brisk effervescence when any part of it is submitted to the action of 

 acids ; and secondly, a more or less abundant mixture of pyrites ; 

 all the bituminous slates when exposed to the action of fire burn 

 with a very strong offensive smell ; but those found below the depth' 

 of eighty yards were not so disagreeable, in that respect, as those 

 which were higher in the stratum. Varieties S3 and 35 were 

 remarkable for their inflamm.ability, and burned with a thick bitu- 

 minous flame, appearing nearly equal in this respect to common 

 coal ; but after the bitumen was exhausted, the remainder was left 

 undiminished in size. The organic remains which I have observed 

 in this stratum as its general characteristics, are impressions of the 

 cornua ammonis and some email bivalve shells. 



The last division which I shall here notice, No. 7 of the Section, 

 represents the alluvial collection of earth which appears to consist 

 almost entirely of the spoils of the neighbouring strata. When 

 these parts were deluged by water, the current evidently appears to 

 have set in from east to west ; for this collection of matter is found 

 to consist principally of a mixture of the different strata which occur 

 to the east of it in a state of decomposition ; and in this mixture 

 which is by no means regular, detached pieces of the beds before 

 alluded to are found unaltered. Of these beds the chalk would 

 expose the greatest surface to the erosion of the water, and next to 

 this the shale would be most extensively acted on ; accordingly we 

 find that the alluvial deposition is composed of white marie and of 

 blue, the former of which being of the least specific gravity, has 

 overspread the higher parts and the summits of the hills, while the 

 lower parts and the vallies are occupied chiefly by the latter. In 

 the blue marie I have frequently found a variety of fossil shells, 



