60 SECTIONAL ADDRESSES. 
Theological prepossessions also maintained the faith of 1831 in the 
Diluvium as the relic of a world-wide flood. The phenomena of the drift 
were then quite unintelligible: but men were collecting and recording 
facts of which they could offer no explanation. Macculloch attributed 
the Parallel Roads of Glen Roy to a lake whose waters were lowered in 
stages by the breaching of a barrier at the mouth of the glen: and his 
inability to explain the barrier did not betray him as to the nature of the 
terraces, in which he was nearer the truth than Darwin who regarded them 
as sea beaches. Jas. Maxwell,1> in 1832, recorded a granite boulder 42 ft. 
by 38 ft. at Appin on Loch Linnhe that appeared to him quite inexplicable. 
It was not until 1840 that Louis Agassiz’ recognition of the glacial origin 
of the British diluvium provided the barrier for Macculloch’s Glen Roy 
lake, the transport of Maxwell’s boulder, and relieved Geology of the 
Noachian deluge. 
3. THE ORIGIN oF OrE-DEPposITs. 
The third geological problem to which the Association directed atten- 
tion was the nature of ore-deposits; and J. Taylor, who was Treasurer 
of both the Association and the Geological Society, at the meeting in 1833 
read a ‘ Report on the State of Knowledge respecting Mineral Veins.’!® 
The explanation of their formation was delayed by erroneous con- 
ceptions as to chemical possibilities. ‘Never,’ said Macculloch,1’ ‘has 
there been a science, unless it be physic, so encumbered with rubbish as 
geology,’ and he complained that geology suffered great discredit owing 
to the extent to which some of its exponents ‘ obtruded their ignorant 
speculations to enthral the mind of the equally ignorant.’ He could have 
justified his criticisms by some arguments on ore genesis. The classification 
of mineral veins had been begun in 1791 by Werner, who attributed most 
of them to the filling of fissures from solutions. Hutton, in 1795, declared, 
on the contrary, the deposition of native metals from solution a ‘ physical 
impossibility,’ and that sulphide ores could only be formed at high 
temperatures ; and he concluded from the absence of any trace of the 
assumed solvent that mineral veins are igneous injections which solidified 
on the escape of the heat. In 1831, in reaction from such speculations 
as to genesis, the standard classifications relied on the form of the deposits ; 
thus, Waldung von Waldenstein in 1824 divided them into sheets, stock- 
works, and masses. Current opinion in England at the time may be seen 
from Taylor’s Report. As the veins of Alston Moor contain lead where 
they traverse the limestone but not where they cross the shale, Taylor 
rejected their formation by igneous injection and attributed ordinary ores 
to sublimation. As it was realised that many mineral veins were too 
wide to have been formed by the infilling of open fissures, the electric 
deposition of the ores was advocated by R. W. Fox in papers to the 
Association!® and elsewhere. The sublimation hypothesis had been 
15 Trans. Geol. Soc. (2), vol. IIT, pt. 3, p. 488. 
16 Rep. B.A. (1833), 1834, pp. 1-25. 
1 Treatise, 1831, vol. I, p. vii. 
18 Rep. B.A. (1834), 1835, pp. 572-4; vol. VI (1837), pp. 133-7; for 1838, 
1839, Trans., p. 90; also Phil. Mag., XIV, 1839, pp. 145-6. Trans. "Geol. Soc. bs 
ser. 2, vol. V, 1840, pp. 497-8. For modern discussion of electric activity on ore- 
deposits, v. R. C. Wells, Bull. U.S.G.S., 548, 1914. 
