250 
YORKSHIRE NATURALISTS AT ROBIN 
HOOD’S BAY. 
May 18th to 2oth, 1907. 
(Continued from page 202). 
GEOLOGICAL SecTion.—Mr. Cosmo Johns writes :—The 
policy of the section in concentrating its attention on some 
special geological feature in each district visited was abundantly 
justified during this particular occasion. The variation in thick- 
ness of the Dogger on both sides of the Peak fault—the 
significant fact that on one side it rested on the Alum Shales 
and was itself reduced to six feet, or occasionally even less in 
thickness, while just across the fault it was much thicker, and 
succeeded Liassic rocks in normal sequence, with the upper 
zone well represented—all lent weight to the view that we were 
here dealing with a most notable example of inter-formational 
or persistent faulting. It is rarely, however, that such move- 
ments can be so clearly demonstrated. 
It is unfortunate that no fuller exposure of the Middle and 
Lower Lias is visible on the downthrow side of the fault, so 
it was not possible to determine whether the pre-Oolite move- 
ment had been preceeded by inter-Liassic dislocations. Quite as 
interesting as the normal movements were the evidences of the 
direction of movement having been reversed at some time, and 
the possible connection of this later adjustment with the 
bifurcating fault on the beach was discussed. What was clear, 
however, is that the earth movements of the Cleveland area 
present a series of problems as complex, and therefore as 
interesting, as any in Britain. That they are chiefly, if not 
entirely, due to gravitational stress makes it just possible that, 
when worked out, they might throw some light upon the 
structure of the Paleozoic rocks that lie buried at some 
unknown depth below. 
It was this concentration of attention on the earth move- 
ments that caused the Dogger to loom so largely during the 
meeting. A ferruginous sandstone—which had probably been 
a calcareous sandstone—with a few badly preserved derived 
fossils, which would otherwise have been hardly noticeable, 
became of great importance. Forming as it does the base of 
the Oolites, and carrying in itself the proofs of the pre-Oolitic 
movement, it was traced along the length of coast visited. It 
Naturalist, 
