C.—GEOLOGY. oF 
claim that it proves the subsidence of an area to an oceanic depth to be 
a physical impossibility are contradicted by geological evidence which 
appear more reliable than calculations based on uncertain assumptions. 
2. Tue Frxity or SPECIES. 
The second hindrance to geological progress in 1831 was the belief in 
the fixity and special creation of species, which was then entrenched by 
theological authority. 
The Geological Committee in 1831 asked J. Phillips to prepare a 
systematic catalogue of British Fossils—a simpler proposition in the days 
of fixed species than it appears now. The chief value of fossils was 
regarded as indices of the age of strata; but their reliability for this 
purpose was not universally accepted, and led to the bout in 1832 between 
the two most forceful personalities in British geology at that time. 
Macculloch—a Franco-Scot from the Channel Islands—was one of the 
most clear-sighted geologists of the early part of the nineteenth century 
and Lyell acclaimed’ him as his greatest geological teacher. In 1831 
Macculloch published ‘ A System of Geology with a Theory of the Earth ’ 
(2 vols.) which involved him in controversies that lasted until the tragic 
ending, four years later, of his rough and stormy life. He was a medical 
man by training, and a chemist by profession. But his main interest was 
Geology, at which he worked with whole-hearted devotion. The bias 
given by his expert knowledge of chemistry may be illustrated by his 
remark that geology is so dependent on chemical principles that it can 
make ‘ scarcely a step without their aid.’ He had roused Murchison’s just 
wrath by the statement that in the ten years preceding 1831, ‘ Geology 
has scarcely received a valuable addition, and not a single fundamental 
one.’ In repudiating this aspersion, Murchison denounced Macculloch 
for neglecting or deriding the value of fossils and claimed them as ‘ the 
very keystone of our fabric.’ The fact that Macculloch had not swept 
to the paleontological day was not due to ignorance but to his recognition 
of the limitations in the interpretation of fossils. He pointed to the 
differences between the living faunas of the English Channel and of the 
Mediterranean as a warning that the correlation of beds by fossils is not 
so simple as some optimists then believed. In regard to some fossils, 
Macculloch was more correct than his critics. To him was due the 
_ memorable discovery at Loch Erriboll in the N.W. of Scotland of fossils 
intercalated in the Highland schists and gneisses. Sedgwick and 
Murchison?® rejected these fossils which, they said, “ we cannot regard as 
organic’; and the discovery was discredited until Salter described the 
larger collection made by the Cornish Customs officer, Charles Peach. 
Macculloch—guided only by lithological evidence—was also correct in his 
- view that the Scottish Torridon Sandstone is a ‘ Primary Sandstone,’ 
whereas Sedgwick and Murchison! had ‘no hesitation’ in identifying 
_ it as Old Red Sandstone. 
9 Proc. Geol. Soc., 1836, vol. II, p. 359. 
10 Trans. Geol. Soc. (2), vol. III, 1829, pp. 155-6. 
Proc. Geol. Soc., vol. I, 1828, p. 79. 
