234 PROCEEDINGS OF SECTION C. 



At Tingha I have observed representatives of the basalts and 

 laterites only. 



MENTION BY PREVIOUS AUTHORS. 



Mr. C. S. Wilkinson, F.Gr.S., etc., describes outliers of red 

 pisolitic iron stone in the Tingha district overlying Tertiary 

 stanniferous gravels, and states that he had not been able to 

 arrive at a definite conclusion as to their origin.* 



Amongst the miners at Vegetable Creek and Tingha, the laterite 

 is known as "Ashes," or " Red Clinkers." 



STRUCTURE. 



Laterite, in all cases observed, occurs in sheets from a few 

 feet to forty feet thick, from half a mile to a mile wide, and is 

 chiefly developed around the points of eruption of the basalt, and 

 consequently for the most part occupies the highest points attained 

 by the volcanic rocks, except in the case of the Wellington Vale 

 Lead. The general shape of these sheets may best be gathered 

 from the geological map accompanying my report on the VegetaVile 

 Creek District, shewing their development in the parish of Lome, 

 County Gough, Vegetable Creek District. The map shews these 

 areas to be of a rudely circular, or elongated-oval shape. Towards 

 the centre of these areas the laterite rises into ridges or suo:arloaf 

 hills, the prominence of which is in inverse proportion to the 

 denudation to which they have been subjected. 



Such prominences may be devided into two classes : — 

 1. Hills. — (^«j Craterif or m hills showing more or less distinct 

 crater rings, which are generally breached at one side. These 

 may be described as composite cones of red scoriro and 

 volcanic dust from fifty to four hundred feet high, the 

 diameter at the summit varying from sixty yards to a 

 quarter of a mile, and the angle of external slope from 20° 

 to 30°. 



Hills of the crater type are best developed, and have 

 suffered least from denudation, in the parish of Lome, 

 where a tolerably perfect old crater is observable in a hill 

 called " The Gap," of which I have elsewhere given the 

 following description : — f 



" The summit is 400 feet above the general level of the 

 lava sheets which radiate from it, and 200 feet above the 

 general level of the neighbouring Palaeozoic rocks. 

 Ascending the " Gap" from the north, the observer passes 

 off" the stony lava on to the red dust and scoriae at a level 

 of about 2,125 feet above the sea. At a level of 2,310 

 feet a round stopper of stony lava is seen in the midst of 

 the red country, and partly encircled by low walls of 



*The Rev. VV. B. Clarke jfives a similar description of the same formation. 

 tGeology of the Vegetable Creek Tin-mining Field, p 34. 



