﻿554 George Barrow — On a Marine Bed in the Yorkshire Oolite. 



It is as follows, in descending order : 



(«) Four feet of very liard close-grained sandstone, containing fragments of 



soft jet and other carbonaceous matter. 

 {b) One foot of sandy impiu'e ironstone, 

 (c) Six feet of dark-brown Oolitic ironstone, slightly magnetic ; apparently 



unfossUiferous. 

 {cl) Two feet of calcareous and ferruginous stone, with a few smaU fossils. 

 (e) Twenty feet of hard, flaggy, micaceous, white sandstone ; passing gradually 



downwards into a sandy shale. 

 (/) One foot six inches of sandy marl. 



{g) Four inches of dense limestone, apparently imfossiliferous. 

 (/;) Five feet of argillaceous, micaceous shale, much resemblmg the shales of 



the Middle Lias. 

 (i) One foot of ironstone, with many specimens of the characteristic Phola- 



domya. 



(c) The position of the above section can best be fixed by the 

 presence of a heap of this ironstone (c) lying on the side of the stream. 



Upon an analysis of the ore being made, it was found to contain 

 an average of more than thirty-five per cent, of metallic iron, one 

 sample yielding as much as forty-two per cent, of that metal. The 

 amount of phosphorus and sulphur was very small, being usually 

 less than O'l per cent, of each. 



After making a careful survey of this district, I have been 

 compelled to arrive at the conclusion that the deposit is of an 

 extremely local nature ; there being the clearest evidence that it 

 does not continue for more than a hundred yards, either to the 

 north, east, or west. Moreover there seems to be a constant tendency 

 to the development of an Oolitic ironstone, usually A'ery siliceous, 

 in the middle of the bed of sandstone : a featvire that can be well 

 seen both in the upper part of the Murk Esk, near Julian Park, and 

 in Wheeldale. 



The bed does not appear to be continuous in a southerly direction ; 

 I rather believe that the ore thins away as rapidly (towards the 

 south) as it can be proved to do in every other direction. 



(/) This bed of marl is in places almost composed of what 

 appears to be a small Gryphcea, which occurs in even greater pro- 

 fusion than does Gryphma cymhium in the Middle Lias. Eunning 

 through the middle of the tnarl is a thin band of soft jet or, perhaps, 

 non-bituminous Coal, with a layer of pyrites above and below. 

 When first dug out, the bed has a bright fracture, and is very hard ; 

 but on exposure to the air it soon becomes so soft that it can be 

 broken to pieces with a very slight blow. 



(^) The lower bed of ironstone does not differ in anj^ essential 

 point from its representative near Goathland ; the characteristic 

 Pholadomya being equally abundant in both cases. There seems to 

 be a greater variety of species in Winter Gill section, but this has 

 scarcely been proved up to the present time. 



This lower bed of ironstone, with its characteristic Pholadomya, 

 has a very much wider range horizontally than might have been 

 expected fi-om its small thickness. It can be easily traced along 

 the steep banks of the upper part of the Murk Esk, and is seen 

 occasionally in the bed and sides of Wheeldale Gill, one of its 



