402 
FIELD NOTES. 
GEOLOGY. 
Striated rock-surface in Ribblesdale.—An interesting 
surface of glaciated Silurian Grit is plainly traceable over an 
area of about fifty square yards on the hillside 320 yards north 
of Arcow, Horton-in-Ribblesdale, at 875 feet above Ordnance 
Datum, and the striz are very distinct over the greater portion. 
A casual observation shows that most of this steep hillside 
bears unmistakable evidence of glaciation, due to the Ribbles- 
dale glacier making its way southwards along this valley. The 
direction of the grooving is practically due north and south, 
and therefore conforms to the general trend of this portion of 
the valley. 
The grits are well exposed in the wood where this striated 
surface is seen, which is about a mile-and-a-quarter almost due 
south of Horton Station. Above this the Mountain Limestone 
of Moughton Scar unconformably overlies the Silurian rocks. 
—E,. E. Grecory, Bingley. 
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MAMMALS. 
Bat mobbed by Swallows.—For two days in succession a 
curious sight was witnessed this week at the Wetwang village 
pond. The sun was shining brilliantly at 2-30 p.m., when a 
little bat was seen hunting backwards and forwards over the 
pond, occasionally pursued by two or three Swallows and 
House-martins, which seemed to wish to drive it off.—E. MAULE 
CoLe, Wetwang, September 13th, 1907. 
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BIRDS. 
Bird Notes from the Whitby District.— Reading Messrs. 
Booth and Fortune’s report of the Vertebrate Section of the 
Yorkshire Naturalists’ meeting at Robin Hood’s Bay last May, 
in your July number, I am induced to send you a few notes on 
some of the birds of the district which may interest a portion of 
your readers. 
SpotreD FiycatcHer.—It is not surprising that this bird 
was not seen during the visit of the Union. As in other districts, 
it was later than usual in putting in an appearance here, the 
first to be observed being on May roth. Later it came in even 
more than usual numbers; so late as September 5th it was 
observed feeding newly-fledged young.* 
* The late arrival of Spotted Flycatchers seems to have been general 
throughout the county this year.—R. F. 
Naturalist, 
