266 YORKSHIRE NATURALISTS’ UNION AT GRASSINGTON. 
and found the greater ... of the rarities mentioned in the 
circular, besides one or two additional. The principal plants were 
Thalictrum minus v. 7 ans Trollius europeus, Viola hirta, 
Geranium sanguineum, Rhamnus frangula, Spirea filipendula, Rubus 
saxatilis, Dryas octopetala (at Arncliffe by Mr. James Backhouse), 
Rosa mollis, Saxifraga hypnoides, Hieracium anglicum (by Mr. Back- 
house at Kilnsey Crag), Pyrola minor, Bartsia odontites, Melampyrum 
pratense, Salix phylicifolia, Polygonatum officinale, Convallaria mazalis, 
and Melica nutans; and of ferns Asplenium viride, A. trichomanes, 
A. ruta-muraria, and Scolopendrium vulgare. No cryptogamist 
reported, so we are without information as to lichens and mosses. 
Mr. B. Holgate, F.G.S., supplies the following report of the 
Geological Section :—-‘ To Rilston and Cracoe’ was the order of the 
day for the geologists who took part in the outing. All were 
in high spirits as, in bright sunshine, they left Skipton about 9.30 
a.m., and went along the pass between Airedale and Wharfedale, 
under the guidance of that most genial and learned member of the 
Geological Survey, Mr. Tiddeman. The craggy edge of Embsay 
oor made a high sky-line to the right, and the old eyrie of the 
Nortons frowned forbiddingly from the summit. One feature of the 
landscape in the valley was most apparent. The latter was studded 
here and there with dome-like knolls, most prominent near the base 
of the crags, which were capped with gritstone. This peculiarity 
struck one at once, covered as the knolls were with the lovely green 
which always marks the presence of limestone. eels contrasted 
with the swarthy heather on the grit moors above, and the ex- 
clamation was often repeated, ‘ What peculiar silt rf followed by 
the question, ‘ How have they been formed?’ It was to examine 
into this problem that the party had come to the spot, and to learn 
from Mr. Tiddeman what he thought on the subject, it being one to 
which he has devoted a great deal of attention. 
Most people who know anything about Yorkshire have heard of 
the great Craven faults, faults so immense that the strata on one side 
of them are something like a mile lower down in the earth than the 
corresponding ones on the other side. Faults are of common 
occurrence, and no one can pass along the main working of a coal 
mine of any size without coming across several of them. Generally 
the strata have been cut off, appearing again it ae be at a few feet 
er yards higher up in the same mine; but as a rule we are right in 
- supposing that though the same strata are at ek levels, they 
follow one another in the same order and thickness. From the 
eeanens made by Mr. Tiddeman, however, it would seem that 
that immense fracture i s the Craven 
re in the crust of the earth, known a heated 
