TRANSACTIONS OF SECTION C. 519 
the description of the lavas. These dykes, &c., are posterior to the volcanic beds 
which they traverse. None, so far as the writer knows, have the characteristic of 
a lava flow. 
They vary much in size, from a few inches thick and a few yards long, 
up to 20 feet: or more in thickness and several miles in length. Two remarkable 
examples of the latter kind occur in South Basutoland, near Mohales’ Hoek. The 
dolerite is columnar, and as straight as if laid out artificially. Small displace- 
ment of the neighbouring strata is a conspicuous feature of these dykes. 
The country owes its present configuration to two series of earth movements : 
one from west to east and the other from south to north, long afterwards. 
There is no evidence of denudation before the deposition of the lavas, and the 
writer is of opinion that the lavas were not all sub-aqueous. 
9. Second Report on the Crystalline Rocks of Anglesey.—See Reports, p. 317. 
10. Report on Life-zones in the British Carboniferous Rocks. 
See Reports, p. 316. 
11. Report on the Erratic Blocks of the British Isles—See Reports, p. 329. 
12. Interim Report on the Correlation and Age of South African 
Strata, &c.—See Reports, p. 328. 
13. Report on the Fossil Flora of the Transvaal.—See Reports, p. 345. 
