George Barroic — On a Marine Bcd in the Yorkshire Oolite. 555 
tributaries. It bas been seen in Hartoft Beck, at the head of 
Glaisdale, and of Grange Becks, and lately my colleague, Mr. 
C. F. Strangways, bas found it in a small tributary of the Bye, 
where the ironstone is 2ft. Gin. 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 Bailway 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 ; chiefly a small 
Gryphcea. 
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 Gryplicea, but with occasional nests of Astarte 
minima, Nucula minima, Littorina, and a few other fossils, all small, 
and appareutly 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 
sandstona 
I believe that this Gryphcea (?) is figured, but not specifically 
named, in Phillips’s Geology of Yorkshire (3rd edit. pl. 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 oceurrence 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 Byedale. 
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 arclueologically, as its outcrop 
is often marked by old heaps of scorke ; 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 
ironstone. 
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 Byedale 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. 
