68 SECTIONAL ADDRESSES. 
6. ‘ Tur Dogma or Untversat ForMATIONS.’ 
In 1831 the stratigraphical principle that Conybeare dismissed as 
‘ Werner’s dogma of Universal Formations’ was being actively discussed. 
He held that in distant lands corresponding formations need not be 
synchronous. This idea—a forecast of Huxley’s doctrine of homotaxis— 
was also adopted by H. D. Rogers in a paper to the Association in 1834, 
when he adopted Lyell’s Kainozoic series not as implying strict identity 
in time but ‘comparative chronological relations’ (Rep. B.A. for 1834, 
1835, p. 32). 
Homotaxis became less important when the age of the earth was 
expanded from the short estimates once advocated. If the earth’s history 
had occupied only a hundred million years, the geological epochs would 
have been so brief that more than one would have been required for the 
migration of a fauna from its centre of origin to its antipodes. Now that 
as much time is available as the greediest geologist can desire, the length 
of the minor divisions of geological time is adequate for the spread of 
faunas throughout any accessible and suitable environment. There is no 
longer any question of the Devonian fauna of Australia having lived at 
the same time as the Carboniferous fauna of Europe. 
The zonal divisions on the other hand are being found less universal 
than had been thought. Faunas spread at various rates and by different 
routes ; hence they do not everywhere succeed one another in the same 
order. 
The view of Oppel (1856, &c.) that Ammonite zones in all parts of the 
world follow in an identical succession, and the expectation that graptolite 
zones are equally regular and world-wide, have proved exaggerations ; 
and Dr. Spath points out that the sequence of zonal Ammonites differs in 
different basins (Geol. Mag., 1931, pp. 184-6). Faunas moreover must 
have often survived only in one area, like the Monotremes and Trigonia in 
Australia, or have taken shelter in one area when they were driven from 
another, such as the Cretaceous types of reptiles in the Eocene of Nigeria 
(Swinton, Bull. G. 8. Nigeria, Bull. 13, 1930, pp. 52-4). Nevertheless, 
the correspondence is remarkable between distant representatives of any 
one geological epoch. Geologists were once confident that the gaps in the 
geological column in Europe would be filled by discoveries elsewhere. 
Such terms as Permo-Carboniferous, Permo-Triassic, Trias-Jura, Cretaceo- 
Tertiary, Cretaceo-Eocene, Mio-Pliocene, &c., expressed the hope that the 
beds thus named would fill gaps in the European sequence. Most of these 
strata have been found to correspond in time with those known in Europe. 
Palzontologically, it is disappointing that the blanks are so widespread 
and that no fossils have been found except the Beltina fauna and obscure 
impressions, older than those known to geologists in 1831. The hope 
that a succession of limestones would be found somewhere to reveal the 
passage from the Paleozoic to the Mesozoic corals is still unfulfilled. 
The lesson from extra-European stratigraphy that seems the most 
remarkable is the world-wide range of the geological Systems and the 
general similarity of geological development. The Systems represent 
definite units in the world’s history and not artificial divisions like a week 
or a calendar month. The physical tests of correlation are of increasing 
value, and the transgressions are more precise time markers than fossils. 
