SCIENTIFIC SUMMARY. 
501 
auriferous solely from their proximity to invisible or now superficial granites. 
The newer outburst cut through strata containing fossils of decided Post- 
oolitic forms, and possibly may be as late as early Cretaceous. 
The Dolichosaurus. — This name has been applied by Mr. H. G. Seeley to 
a peculiar, lizard-like serpent of the Chalk formation. Mr. Seeley’s descrip- 
tion of the creature indicates for it a position between the serpent and the 
lizard. 
Drift Deposit on the Weaver Hills. — Mr. E. Brown’s paper on the above, 
which was read before the British Association at Nottingham, records some 
useful observations. It dealt with the remarkable deposit of sand and clay in 
the south and south-west flanks of Weaver and of Caldon low, and which 
seems to be of considerable antiquity. It has been preserved at an elevation 
of between 1,000 feet and 1,100 feet from subsequent entire denudation by a 
ridge of York-dale rocks that stretches to a considerable height to the south- 
west of the above-mentioned hills. The deposit consists of pure white sili- 
ceous sands, of white plastic clay, and of other materials derived apparently 
from the degradation of the Millstone Grit, the Bunter, and other rocks of 
the district. The clay and sands consist almost entirely of silica and alumina, 
and they are extensively used for the making of fire-bricks, and for the build- 
ing and lining of smelting-furnaces, and for other purposes when a capacity 
for resisting high temperature is required. This bed is overlaid by the boulder 
clay deposit of the district, and the author hazarded the suggestion that it may 
have been contemporary in its origin with certain of the later tertiaries, as, 
for instance, the Norwich Crag. 
The Metamorphic and Lower Silurian Rocks of Ayrshire. — Mr. J. Geikie 
has published a memoir on the above rocks situate at Carrick, in South 
Ayrshire. He divides the metamorphic rocks into four series : — (1) Feld- 
spathic rocks ; (2) diorites ; (3) serpentine ; and (4) altered limestone and calca- 
careous grauwacke. Further, he sub-divides the feldspathic rocks into ( a ) 
amygdaloid ; (6) porphyry ; (c) brecciseform ; and (d ) finely crystalline fel- 
stones. He divides the serpentine rocks into schistose and compact. After 
giving numerous details, he arrives at the following conclusions : — (1) That 
the strata owe their metamorphism to hydrothermal action. (2) That the 
varying mineralogical character of the rocks is due principally to original 
differences of chemical composition, and not to infiltration of foreign matter 
at the time of metamorphism. (3) That the highly alkaline portions of the 
strata have been most susceptible to change. (4) That in beds having the 
same composition, but exhibiting various degrees of alteration, the intensity 
of the metamorphism has been in direct proportion to the amount of water 
present in the strata. (5) That in some places the rocks have been reduced 
to a pasty condition. 
How many Crags are there ?■ — In answer to this question, Mr. J. E. 
Taylor says four : — The coralline, red, Norwich, and upper. Published tables 
show that as regards the percentage of recent and extinct shells, and also the 
number of species, there is a greater difference between the red and Norwich 
crags than between the red and the upper. The difference between the two 
latter was hardly in the proportion of 3 to 2, whilst that of the two former was 
more than 3 to 1. Still there has for some time been a growing conviction of the 
closer relationship of the red and Norwich than of the red and coralline crags. 
