496 
NATURE 
[ Sept. 23, 1886 
Yuesday.—Reports and papers on pure and more chemical 
physics. Technical chemistry in B. 
Wednesday.—Arrears and papers on minor or semi-technical 
experimental details. Simultaneous sub-section, if necessary, 
for clearing off arrears without haste. 
It may be felt that this means a hard week’s work. 
does. Attendance at these meetings, if attentive, is no child's 
play. But if any diminution is necessary, I submit that it is 
better to shorten each day’s sitting than to lessen the number of 
days. One is fresh enough at 10, when the committee work 
begins, but pretty tired and hungry at 3. If interest dwindles, 
and papers begin to hurry themselves off without discussion, or 
to drone themselves dismally through, it is far better for the 
Section to rise at 2, instead of constraining itself to continue the 
process till the allotted hour. On the other hand, if interesting 
discussions arise, and attendance is good, it is very well to be 
able to continue the sitting till 3 or even longer. Though, 
indeed, Thursday is the only day on which a sitting may happily 
be continued beyond 3 without being disturbed by a committee 
meeting. 
I have now said my say. I offer no apology for treating the 
subject, because my single aim in doing so has been to 
endeavour to do something to promote the usefulness and 
success of these meetings. OLIVER LODGE 
University College, Liverpool, September 13 
Well, it 
The Geological Age of the North Atlantic Ocean 
WHILE the interest attaching to Sir William Dawson’s Presi- 
dential address at Birmingham is still fresh, I wish to be allowed 
to offer a few observations on that part of it which deals with 
the geological age of the North Atlantic Ocean. The President 
in referring to those writers who, like Mr. Crosby in America, 
Mr. Mellard Reade and myself in Britain, maintain that the 
North Atlantic and the American continent have in the main 
changed places in Palaeozoic times, makes the following state- 
ment. Admitting the correctness of the facts as to the swelling 
out of the Palaeozoic sediments in the direction of the Atlantic 
seaboard, he endeavours to account for these very striking pheno- 
mena thus: ‘‘I prefer, with Hall, to consider these belts of 
sediment as in the main the deposits of northern currents, and 
derived from Arctic land, and that, like the great banks of the 
American coast at the present day, which are being built up by 
the present Arctic current, they had little to do with any direct 
drainage from the adjacent shore.” Now, in reading this 
passage it occurs to me that Sir W. Dawson must have felt he 
had a very questionable case when he attempted to support it 
by such an hypothesis. To liken the great sheets of sediment 
which spread themselves sometimes over half the North Ameri- 
can continent south of the Great Lakes to the banks heaped up 
along the Atlantic coast is a point of analogy in which, probably, 
he will find few to concur. The Paleozoic sediments are certainly 
not banks, but sheets originally spread over the sea-bed, and dis- 
tributed according to certain recognised laws of increase and 
decrease of thickness. 
But, putting this point aside, I may be allowed to ask, How 
can we suppose the existence of a northern current bringing 
sediment from the Arctic regions, and spreading it over Eastern 
America, unless there was at the same time a coast-line to guide 
the current in taking a southerly direction ; and if such a coast- 
line existed, must it not have lain along the eastern American 
shore, because the American continent itself was then sub- 
merged? If we examine a current-chart of the globe, we find 
that all the N.-S. oceanic currents flow along the continental 
shores and take their directions from them. If America and 
the Atlantic, south of the Arctic regions, were both oceanic in 
Palzeozoic times, then the current would not have been southerly, 
but westerly or easterly, according to circumstances, certainly 
not flowing from north to south ; therefore this explanation for 
the distribution of the Palaeozoic strata cannot, I venture to say, 
bear the test of examination. 
Again, the President states: ‘‘It is farther obvious that the 
ordinary reasoning respecting the necessity of continental areas 
in the present ocean basins would actually oblige us to suppose 
that the whole of the oceans and continents had repeatedly 
changed places.” Now, as regards the North Atlantic, this is 
an objection which is purely imaginary ; because the evidence 
goes to show that it remained in the condition of a continent all 
through the Paleozoic ages, with, of course, ever-varying mar- 
gins ; and it is only so far (as a writer in the Atheneum, Sep- 
| 
tember 4, has properly pointed out) that I have argued in favour 
of its continental condition. But undoubtedly the arguments 
in favour of the interchange of ocean and continent during 
Paleozoic times, as applicable to North America, would be 
found to apply more or less strictly to other oceans and con- 
tinents, owing to the wide distribution of the formations of this 
period over the present continental areas. Northern and Cen- 
tral Africa and Greenland may prove exceptions ; but apart from 
these tracts, Palaeozoic strata appear to have been distributed 
(prior to denudation) over by far the greater portions of the con- 
tinents, and the sediments must have been derived from the 
adjoining continental areas, which are now covered by the 
waters of the ocean. 
The question between the President and myself is mainly 
this: Did the sedimentary strata of the Paleozoic period of 
North America come from lands lying around the Arctic Circle, 
or from others occupying the position of the North Atlantic ? 
American geologists have a favourite theory that the Arctic 
regions have been the originating lands, but I venture to repeat 
that if it be allowed as a general principle that the originating 
lands lay in the direction towards which thesedimentsthicken, and 
opposite to that in which the limestones are most developed, the 
conclusion is inevitable that the Atlantic was in the main a land- 
surface in Paleeozoic times. All the Palzeozoic formations of 
North America point to this conclusion, as I have on former 
occasions attempted to show,! and this, regardless of the ques- 
tion whether or not there was also land along the Arctic Circle, 
Throughout the Silurian, Devonian, and Carboniferous epochs 
marine limestones were in course of formation mainly over the 
regions west of the Mississippi, and sediments mainly east of 
that line and chiefly in the Appalachian region. The general 
direction of the swelling out of the sediment is (if I mistake not) 
rather south of east than north of east. Thus, the ‘‘ Potsdam 
beds” appear to swell out towards the E.S.E.; the ‘* Hudson 
beds,” S.E., and S.S.E.; the ‘*Hamilton beds” of the 
Devonian, towards the E. or E S.E. ; and different members of 
the Carboniferous series swell out N.E., E., and S.E. On the 
whole, and as a general result, the centre from which the sedi- 
ments appear to have been chiefly distributed seems to have 
lain around the point intersected by the parallel 30° N. lat. 
and the meridian of 60° W. long., except in the Carboniferous 
period, when the originating lands appear to have lain in the 
region of the first Atlantic cable, between Newfoundland and 
the British Isles, and which lands were probably continuous with 
those of the Arctic continent. 
I wish, in conclusion, to take this opportunity of adding a few 
words in reference to the Archzean rocks. I am much disposed 
to concur in the view of Sir W. Dawson—that the fundamental 
gneissose beds of the Archzean period may have had a different 
origin from the metamorphic strata of succeeding periods, and 
that they may not have been originally sediments. This obser- 
vation does not, however, apply to the schists, limestones, and 
quartzites which succeed them, and which sometimes include 
beds of gneiss, as in Scandinavia. From this point of view, the 
birthday of the Atlantic continent may not have dated farther 
back than the commencement of the Palzeozoic age—represented 
in Britain by the Cambrian, and in America by the Potsdam, 
sandstone. Asa continent it remained till the close of that age. 
To what extent it survived the terrestrial movements which 
closed that epoch I am not prepared to say. 
Dublin, September 15 EDWARD HULL 
Earthquake at Sea 
CAPTAIN H. J. OLSEN, commanding the brig Wilhelmine of 
Drammen, reports that, on the rst inst., being by dead reckon- 
ing in lat. 50° 10’ N., long. 1° go’ W., he observed, between 
3.30 and 4 p.m., three rumblings at short intervals, during which 
the ship was felt to tremble violently, so that both the bulwarks 
of the cabin and plates on the table clattered. The wind was 
north-west, with a gentle breeze, and the ship was on the star- 
board tack. H. Moun 
Det Norske Meteorologiske Institut, 
Christiania, September 15 
Peripatus 
Nature for July 29 (p. 288) mentions that Perzpatws has been 
taken at Demerara. It may interest some of the readers of 
© Scient. Trans. Roy. Dublin Soc., vol. iii. 2 ser. p. 305 (1885), and 
‘*Contributions to the Physical History of the British Isles,”’ p. 27 e¢ seg. 
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