436 Miss C. A. Raisin—Geology of Africa. 
the present occasion an expression of his indebtedness to Professor 
McKenny Hughes and MM. Dupont and Dollo for the opportunity 
of studying the specimens in the Museums of Cambridge and 
Brussels. 
(To be continued in our next Number.) 
IJ.—Conrrisutions to THE GroLtocy or AFRIOA. 
By Miss Carurrinu A. Ratsin, B.Sc. 
I.—Rockx Specimens From Upper Ecyret. 
HE following notes have been drawn up from a study of 
specimens which were collected by G. F. Scott Elliot, Esq., 
during the earlier of two recent expeditions in Africa. He followed 
the Nile to somewhat beyond the second cataract, and brought back 
more than 130 examples of various rocks. The collection was sent 
to University College for examination, which I was allowed to 
undertake by the kindness of Professor Bonney, to whom I am 
further indebted for much help and advice on points of difficulty. 
A detailed description has been furnished to Mr. Scott Elliot to 
be included in the account of his journey, which it is to be hoped 
will be published before long. It may, however, be useful to have 
a short summary of the chief points of geological interest for general 
reference in an easily accessible publication. 
A few illustrations of the well-known sandstones and limestones 
were brought from near Cairo, but with the exception of these (four 
in number) all the specimens were obtained from Upper Egypt, 
between latitude just north of 24° N. near the first cataract, and 
about latitude 21° 380’ N., south of Sarras, beyond the second 
cataract. 
As many writers have now described, the sedimentary strata rest 
over a wide area in Kgypt, Sinai and Palestine upon an old crystal- 
line series.!. While certain at least of these latter rocks are evidently 
igneous, others are described as presenting difficulties in field 
examination, and similarly, gradations from granite to gneiss can 
be traced in microscope slides. Thus, although a crystalline series 
of Archean aspect doubtless occurs, traversed by ancient dykes and 
intrusions,” it is not easy, and in many cases not possible, to separate 
the hand specimens (even when illustrated by microscopic sections) 
into the two classes. 
Normal granites are shewn in the well-known coarsely por- 
phyritic variety from the Assouan quarry, and in several which 
have a binary character. In the more or less gneissoid rocks (of 
which some at least are probably Archean) the foliation exhibits 
differences. In certain sections zones of mosaic undulate around 
1 See description of specimens by Prof. T. G. Bonney, in Grou. Mac. 1886, 
Dee. III. Vol. III. pp. 108-106; Prof. Dawson, Gror. Mac. 1888, pp. 439, 440, 
481,482; K.A. von Zittel, ‘‘Ueber den geolog. Bau der libyschen Wuste,’’ 1880, p. 9. 
2 See references above; and also ‘Géol. de Palestine,’ M. L. Lartet, p. 55. I 
have to thank Mr. L. L. Belinfante, B.Sc., the Curator of the Geological Society, 
for kindly giving me facility to examine the collection brought by Mr. J. C. 
Hawkshaw, which was interesting for comparison, and included some similar types. 
