Correspondence—B. Hobson. 95 
apparently in North Mashonaland by a thick series of grits, resembling 
microscopically the Moine Gneisses of the Scottish Highlands. The 
series contains pebbles of granite free from microcline, and banded 
ironstones. 
The thick crystalline limestones overlying the conglomerate series 
contain chert and dolomite, the latter rock occurring also as ait 
alteration product from serpentine. Graphite also is found, and is 
attributed to the insolubility of carbonaceous matter in a highly 
siliceous magma. Contact alterations of the limestones by the granites 
are described. 
The granites occupy the greater part of the area dealt with, and 
their intrusive character as regards the metamorphic rocks is shown. 
The normal granites are biotite-bearing, and have microcline as the 
dominant felspar; they never contain hornblende or muscovite. 
Patches of micropegmatite are included in the microcline, proving that 
the ‘ eutectic’ was not the final residuum of crystallization. Orthite, 
as well as epidote, occur in most sections cut from the Matopo 
Granite, and the author compares the mixed rocks of the gneissose 
edges of the granite with the ‘Fundamental Gneiss’ of Canada and 
other regions. 
The sedimentary series is subdivided as follows :— 
Zambesi Basin. Thickness in feet. 
Taba’s Induna Series . : : é 3 : ° = 200 
Forest Sandstones and Basalts : : : : ; - 1000 
Escarpment Grits . . 5 : 2 ; : 5 . 400 
Upper Matobola Beds (coal-bearing) F : : : a 300 
Busé Beds (local only ?) Naley- ‘ : : : 22 300 
Lower Matobola Beds (coal-bearing) : ; : 3 - 200 
Sijarira Series . ‘ away : : : : . 2000 
Limpopo Basin. 
Tuli Lavas. 
Coal Beds. 
Unconformity. 
Samkoto Sandstones. 
No fossils are recorded, other than silicified wood, except in the ~ 
coal-bearing beds, in which occurs Paleomutela Keyserlingi of the 
Russian Permian, as also plants. 
Various igneous rocks are described, including the great mass of 
picrite extending nearly across Rhodesia, which the author considers ° 
to be intrusive along a thrust-plane. 
The paper concludes with a description of the diamond-bearing beds 
of Rhodesia, which resemble those of Kimberley, and also contain 
fragments of eclogite. 
CORRESPONDENCE. 
= 
THE PRICE OF GEOLOGICAL SURVEY MAPS. 
Sir,— A recent decision of the Treasury, that the prices charged for 
all Government publications should be sufficient to cover the cost of 
their production, is calculated to discourage the pursuit of science and 
