Page 15 - Global Tectonics

2 CHAPTER 1

1.1 CONTINENTAL

DRIFT

Although the theory of the new global tectonics, or
plate tectonics, has largely been developed since 1967,
the history of ideas concerning a mobilist view of the
Earth extends back considerably longer (Rupke, 1970;
Hallam, 1973a; Vine, 1977; Frankel, 1988). Ever since
the coastlines of the continents around the Atlantic

Ocean were first charted, people have been intrigued by
the similarity of the coastlines of the Americas and of

Europe and Africa. Possibly the first to note the similar-
ity and suggest an ancient separation was Abraham
Ortelius in 1596 (Romm, 1994). In 1620, Francis Bacon,
in his Novum Organum, commented on the similar form
of the west coasts of Africa and South America: that is,
the Atlantic coast of Africa and the Pacifi c coast of South Figure 1.1 Snider’s reconstruction of the continents
America. He also noted the similar confi gurations of (Snider, 1858).
the New and Old World, “both of which are broad and
extended towards the north, narrow and pointed
towards the south.” Perhaps because of these observa- Alexander von Humbolt noted the geometric and geo-
tions, for there appear to be no others, Bacon is often logic similarities of the opposing shores of the Atlantic,
erroneously credited with having been first to notice but he too speculated that the Atlantic was formed by

the similarity or “fit” of the Atlantic coastlines of South a catastrophic event, this time “a flow of eddying waters

America and Africa and even with having suggested that . . . directed first towards the north-east, then towards
they were once together and had drifted apart. In 1668, the north-west, and back again to the north-east . . .
François Placet, a French prior, related the separation What we call the Atlantic Ocean is nothing else than a
of the Americas to the Flood of Noah. Noting from the valley scooped out by the sea.” In 1858 an American,
Bible that prior to the flood the Earth was one and Antonio Snider, made the same observations but postu-

undivided, he postulated that the Americas were formed lated “drift” and related it to “multiple catastrophism”
by the conjunction of floating islands or separated from – the Flood being the last major catastrophe. Thus

Europe and Africa by the destruction of an intervening Snider suggested drift sensu stricto, and he even went so
landmass, “Atlantis.” One must remember, of course, far as to suggest a pre-drift reconstruction (Fig. 1.1).
that during the 17th and 18th centuries geology, like The 19th century saw the gradual replacement of
most sciences, was carried out by clerics and theolo- the concept of catastrophism by that of “uniformitari-
gians who felt that their observations, such as the occur- anism” or “actualism” as propounded by the British
rence of marine fossils and water-lain sediments on high geologists James Hutton and Charles Lyell. Hutton
land, were explicable in terms of the Flood and other wrote “No powers are to be employed that are not
biblical catastrophes. natural to the globe, no action to be admitted of except

Another person to note the fit of the Atlantic coast- those of which we know the principle, and no extraor-
lines of South America and Africa and to suggest that dinary events to be alleged in order to explain a common
they might once have been side by side was Theodor appearance.” This is usually stated in Archibald Geikie’s
Christoph Lilienthal, Professor of Theology at Königs- paraphrase of Hutton’s words, “the present is the key
berg in Germany. In a work dated 1756 he too related to the past,” that is, the slow processes going on at and
their separation to biblical catastrophism, drawing on beneath the Earth’s surface today have been going on
the text, “in the days of Peleg, the earth was divided.” throughout geologic time and have shaped the surface
In papers dated 1801 and 1845, the German explorer record. Despite this change in the basis of geologic