26 PROCEEDINGS OF THE GEOLOGICAI. SOCIETY. [June 4, 



Conclusion. 



After having observed the facts detailed in the foregoing paper, 

 the author has arrived at the following conclusions : — 



1st. That although the Lancashire coal-field is 6600 feet in thick- 

 ness, and is probably the most perfectly developed coal-field in En- 

 gland, still it has never been seen to graduate upwards into the new 

 red sandstone, and, consequently, that its upper boundary must be 

 considered as unascertained. 



2nd. That on comparing the Lancashire coal-field with that of 

 the south-west of Yorkshire and Derbyshire, the latter exhibits a 

 deficiency of 837 yards of the middle and upper measures. 



3rd. That the new red sandstone formation is found resting upon 

 coal-measures of all ages, and scarcely ever at different places on 

 rocks of the same age, so that it cannot with propriety be said to 

 bound, but only to cover them. 



4th. That where coal-measures have been found on their rise 

 outcropping against the new red sandstone, the latter bed, so far as 

 has been yet proved, always indicates that the coal-measures exist 

 beneath it, but that the dislocation is of great extent. 



5th. That in all cases where seams of coal have been followed on 

 their dip under the new red sandstone, they have been found to 

 continue under it without any perceptible difference either in their 

 inclination or quality. 



6th. That the dislocations in the coal-field may be classed under 

 two heads, namely the older ones, produced before the deposition of 

 the upper new red sandstone, and the newer ones which have been 

 produced since, but that the former have been in some degree af- 

 fected by the movements which produced the latter. 



7th. That the new red sandstone formation is very irregularly de- 

 posited over the underlying carboniferous strata, and that its two 

 lower members are frequently either very slightly developed or al- 

 together wanting, which seems to indicate that these lower members 

 repose in great troughs and hollows of the coal-field, which had an 

 irregular surface, over which the waters of the new red sandstone 

 sea flowed and deposited the various beds. 



June 4, 1845. 



The following communications were read : — 



1. An account of the Finb TivsT which often falls on Vessels in the 

 Atlantic Ocean. By Charles Darwin, Esq., F.R.S., F.G.S. 



Many scattered accounts have appeared concerning the dust which 

 has fallen in considerable quantities on vessels on the African side of 

 the Atlantic Ocean. It has appeared to me desirable to collect these 

 accounts, more especially since Professor Ehrenberg's remarkable 

 discovery that the dust consists in considerable part of Infusoria and 



