﻿George Barrow — On a Marine Bed in the Yorkshire Oolite. 555 



tributaries. It has been seen in Hartoft Beck, at the head of 

 Glaisdale, and of Grange Becks, and lately my colleague, Mr. 

 C. F. Strangways, has found it in a small tributary of the Eye, 

 where the ironstone is 2ft. Bin. thick, and has a close resemblance 

 to a similar seam in the Middle Lias. 



In the north and east the whole fossiliferous part of the bed thins 

 away gradually, until, at Loftus Eailway Station, there is a section 

 of the shales with thin wedges of shaly ironstone, the whole being 

 only two feet thick, and containing but few fossils ; chieiiy a small 

 GryplKsa. 



At Kettleness, however, there is a section showing the typical 

 sandstone, ferruginous in parts, with about eight feet of shale 

 beneath. About six to seven feet down in this shale is a thin band 

 of fine dense ironstone-doggers; their base being a mass of fossils, 

 mostly the small GrypTicea, but with occasional nests of Astarte 

 minima, Nucula minima, Littorina, and a few other fossils, all small, 

 and apparently dwarfed. Below this is a foot of shale, perhaps 

 more, resting on a bed of hard ironstone, about a foot thick, sandy 

 at the base, and the upper part having a blue tint and of an oolitic 

 structure. Beneath this ironstone again is a mass of false-bedded 

 sandstone. 



I believe that this GrypJicea (?) is figured, but not specifically 

 named, in Phillips's Geology of Yorkshire (3rd edit. pi. ix. fig. 26) ; 

 and from its appearance always at the top or base of these thin 

 marine beds, I feel sure it is essentially a brackish- water shell ; and 

 from its occurrence alone in the Loftus section, and being only 

 accompanied by a few small species at Kettleness, we may venture 

 to say that the bed dies out, or at least becomes less marine in 

 character as we go north and east, and thickens south and west, 

 as is proved by the rapidly increasing thickness of the fossiliferous 

 ironstone going from the coast to Goathland, Glaisdale, and Ryedale. 

 At the same time we believe it to become thinner again south of a 

 certain point which we cannot yet accurately define ; the whole bed 

 forming an extremely thin but very persistent wedge, over the 

 whole of the East Yorkshire area. 



This sandstone bed is interesting archseologically, as its outcrop 

 is often marked by old heaps of scoriee ; the thin bands of ironstone 

 in the sandstone being the source of the ore : the two bands of 

 ironstone that occur in the shale underlying never having been 

 used. Holey Pits, near Egton Bridge, show a number of small 

 holes formerly made in the sandstone in order to win or obtain the 

 ii'onstone. 



This short notice is sent in the hope that others may carefully 

 study the fauna of the lower band of Ironstone, from which, in 

 the Ryedale district, a large addition may be made to the present 

 number of known species of fossils. A fuller description of the bed 

 will be published in the Survey Memoir on the districts in which it 

 is so well displayed. 



