Reports & Proceedings—Yorkshire Naturalists Union. 91 
“ The Geology of Killifreth Mine.” By H. Kitto. 
A detailed description of the geology of the mine and the lode 
characters. The country rock is mostly slate, but a quartz porphyry 
dyke is cut in two levels, and a tongue of granite is met with about 
40 fathoms from surface and a tongue of schorl rock nearer surface. 
The minerals of the lodes include cassiterite, wolfram, mispickel, 
pyrite, blende, molybdenite, and smaltite. Several of the lodes 
show filling in two distinct stages, and the values are high but patchy. 
The author discusses an interesting case of a lateral fault without 
vertical displacement. 
‘The Geology of Carn Marth.” By G. MacPherson. 
The geology of the district round Carn Marth is described with 
special reference to the igneous rocks. The so-called differentiated 
granite of the top of Carn Marth is considered by the author to be 
three successive intrusions of different types of granite; first the 
coarse-grained type, second the fine-grained oranite without 
tourmalinization, third the tourmalinized fine-grained granite. 
Pegmatite and aplite veins also occur in the granite. 
YoRKSHIRE NATURALISTS UNION. 
December 4, 1920.—At Bradford. 
Presidential Address by Professor J. E. Marr, 8c.D., F.R.S. 
Professor Marr dealt with the tract of country comprising north- 
west Yorkshire and parts of the country lying to the north, where 
Carboniferous rocks are nearly horizontal over a wide area. He 
maintained that this tract had formed a rigid block of earth’s crust, 
- certainly since the beginning of Carboniferous times, and possibly 
for a longer period. Referring to Mr. R. H. Rastall’s work on the 
Ingletonian rocks, which contain fragments of crystalline schists, 
he argued that a core of ancient rocks lay under the Carboniferous 
strata, and that newer rocks had been folded against this core at 
various times on the south, west, and north. The rigid block is 
bounded on the west and south by the Pennine, Dent, and Craven 
faults, and he gave reason for supposing that as movement went on 
against the block at different times, parts of the compressed rocks 
were added to the rigid block, causing it to grow outwards, the newer 
fault-lines lying further away from the centre of the block than the 
older ones. He supported this by special reference to the tract of 
Edenside, west of the Crossfell portion of the Pennine Chain, where 
there appeared to be evidence of faulting at the end of Carboniferous 
times, subsequently in Permo-Triassic times, and later stiil possibly 
in the Tertiary era. Similar changes seemed to have occurred to 
the south, along the Craven system of fractures. There was, however, 
some difference in the nature of the earth-waves affecting the areas 
to the west and south of the rigid mass. The former were com- 
parable with the great rollers of the ocean, those of the latter rather 
