THE 
GEOLOGICAL MAGAZINE. 
NEW, SERIES.,, DEGADE.V....VOL..VIl. 
No. I.— JANUARY, 1910. 
ORIGINAL ARTICLES. 
a 
I.—On Oxivinr Noputes 1n tHE Basatr or Catron Hitt, 
DERBYSHIRE. 
By H. H. Arnotp-Bemrosz, J.P., Se.D., F.G.S. 
(PLATES I AND II.) 
InrRoDUCTION. 
FYVHE object of this paper is to place on record the occurrence of 
olivine nodules in a British basalt which, though closely allied in 
structure to some of the Tertiary basalts of the Continent, belongs 
undoubtedly to the Carboniferous age. Olivine nodules frequently 
occur in the Continental basalts and have been considered by some 
writers as inclusions of peridotites, but by others as segregations from 
the magma. 
I can find no description of olivine nodules from any British basalt 
in which the olivine is in a fresh condition. The nearest approach to 
such a nodule is that described by Mr. 8. Allport, from Ballybrood, 
in the county of Limerick.! The rock, he says, ‘‘ contains small 
patches of red and green serpentine scattered through it.”’ ‘‘ In one 
of the largest patches there are several grains of olivine, and an 
examination in polarized light shows that it was originally a nest of 
olivine which has been almost completely altered to serpentine.” 
Dr. Teall,” in referring to Mr. Allport’s description, remarks that 
‘¢ this is an extremely important observation, because it is the only one 
yet made of the occurrence of anything like an olivine nodule in any 
British basalt”. 
In 1894, in describing a basalt from Calton Hill, Derbyshire, 
I mentioned the presence of olivine in small groups or nests of 
erystals*; and in 1907 I stated that I had found olivine in small 
nests of bottle-green colours. The largest nest of olivine and augite 
then found by me measured only 2°7 X 2:2 mm. under the microscope. 
Trial holes have recently been made in Calton Hill, Derbyshire, 
which is a volcanic vent of Carboniferous age, and a level has been 
1 «Qn the Microscopic Structure and. Composition of British Carboniferous 
Dolerites’?: Q.J.G.S., 1874, vol. xxx, p. 552. 
2 British Petrography, 1888, p. 246. 
3 Q.J.G.8., 1894, vol. 1, p. 621. 
+ Q:J:G-8:, 1907, vol. lxiii, p. 252. 
DECADE V.—VOL. VII.—NO. I. 1 
