﻿part 3] STANNIFEROUS DEPOSITS OP KINTA DISTRICT. 



189 



It is true that marks of glaciation cannot be expected on lime- 

 stone bed-rock which has been attacked to such an extent that 

 any glaciated pavements that it may have once formed would have 

 disappeared long ago. But boulders in clays, which are stated to 

 have preserved their angularity owing to transport by ice and 

 not by water, would be reasonably expected to have preserved 

 some signs of polished surfaces and striae. The absence of angular 

 corners clue to subsequent solution could be understood; but 

 the circumstances which enabled the boulders in a glacial clay to 

 preserve their angularity, and yet to lose their polished surfaces 

 and striae, are difficult to imagine. 



Fine clay in glacial deposits, being formed by the powdering of 

 the minerals of the rocks over which the ice has passed, would be 

 expected to carry, in a finely comminuted state, representatives of 

 such minerals as are especially resistant to weathering. Where, 

 consequently, a mineral such as cassiterite is present as a coarse 

 material in glacial clays, it is to be expected that it is present also 

 as a fine flour. Cassiterite is brittle, comparatively soft, and as 

 insoluble as silica, which is present in the supposed rock-flour, so 

 that glacial clay rich in coarse angular tin-ore should give, in its 

 finest parts, chemical reactions for tin. Several tests which I 

 carried out on this fine material have failed to reveal tin. 



The Restricted Areas to which the supposed 'Glacial 

 Clays' are confined, even in the Kinta District. 



If the ' clays and boulder-clays ' belong to the Lower Gondwana 

 Rocks (they have been correlated with the Talchir proper), and 

 hence are older than the phyllites, quartzites, and indurated shales, 

 it is reasonable to expect them to underlie most of these latter 

 rocks at least in the Kinta district, for in India the Talchir proper 

 (the actual glacial bed) is the most widely spread of all the 

 Gondwana divisions. 1 A reference, however, to Mr. Scrivenor's 

 map will show that they have been proved only in a few restricted 

 patches, even in the Kinta district ; and it is of the greatest signi- 

 ficance, bearing in mind their great economic importance, that 

 these supposed glacial stanniferous clays have never been dis- 

 covered underlying the ' younger Gondwana Rocks ' in the numerous 

 cuttings in the district, except near the foot of the granite ranges, 

 where, according to my contention, they are the result of weathering 

 in situ of the schists and phyllites. 



Absence of Glacial Tin-Ore Deposits in other parts of 

 Malaya and in the Neighbouring Countries. 



No tin-ore bearing clays in Malaya, in the neighbouring 

 countries, nor in the Far East, have been claimed to be of glacial 

 origin, except those' of the Kinta district. 



1 E. V. Vredenburg, ' Summary of the Geology of India ' 2nd ed. Calcutta, 

 1910, p. 52. 



