Oct. 8, 1885] 
NATURE 
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difficult in the extreme. The article is of special valu2 at the 
present moment, when the question of trade routes int» South- 
Western China has assumed so much prominence. 
THE BRITISH ASSOCIATION 
SECTION C—GEoLocy 
Some Resuits of a Detailed Survey of the Old Coast-Lines near 
Trondhjem. Norway, by Hugh Miller, F.G.S., H.M. Geological 
Survey.—During a short visit to Norway in October, 1884, it 
appeared to the author that the best way to help to a solution of 
the vexed questions connected with the coast-terracing of Nor- 
way was to execute a careful survey of a few square miles of 
some suitable coast-region upon a sufficiently large scale. The 
neighbourhood of Trondhjem is remarkably well suited to this 
purpose. The map employed was partly a municipal chart on 
the scale of I-10,000, and partly an enlargement of the Ordnance 
map. ‘The limit of all the terraces and marine deposits is the 
fanous “‘strand line” west of the town, a double range of old 
coast-cliff cut in the rock of the mountain-side. Its upper line 
is 580 feet above the sea, and answers to the “ marine limit” 
over Norway generally. Numbers of level terrace-lines have 
been incised—chiefly in greenish clays, like brick-clays—all 
along the arable slopes east of the town between this rock- 
terrace and the sea. Aove the Bay of Leangen, two miles 
east of town and river, and far beyond all erosive influence of 
the latter, thirty of these lines were mapped one above another 
in the first 300 feet of ascent, a distance of one and a half mile. 
Many of these are small but extremely distinct, the earthy clays 
being well suited to retain sharp impressions of successive sea- 
margins, which these unequivocally are. The present coast-line, 
neatly etched out by the waves in Trondhjem and Leangen 
Bays, is the key to these tiers of older ones. It also resembles 
them in having made little or no impression where the coast 
becomes rocky, the lines of incision in both cases stopping short 
at oice when they reach the harder material. The old coast- 
lines are most numerous in well-sheltered positions. Thus a 
sinzle pair of large terraces in an exposed situation east from 
Christiansten, where they face the open water of the fjord and 
the prevalent north-westerl, storms, is represented in the recess 
above Leangen Bay by ten or twelve. The same fact is brought 
out on rising from this recess to the higher and more exposed 
ground. Thus, while thirty-three or thirty-four terrac*s are 
mapped below 350 feet (approximate) elevation, only niie or 
ten appear between that level and the rock-terraces of the upper 
marine limit, the numerical average height of the terraces thus 
risinz by more than a half. In recesses of the coast further east, 
but beyond the map, these upper terraces seem to be preserved 
in considerably greater numbers. The number actually mapped 
was forty-three, or, with the two rock-terraces, forty-five. The 
largest nunhber of terraces hitherto described at any one place 
in Norway seems to have been eighteen. Some of the general 
conclusions of the author are as follows :—-(1) These terraces are 
all post-glacial, 7.¢. formed since the rock-glaciation of the dis- 
trict. This is confirmed by the coadition of the high coast-cliff, 
which has been cut in ice-rounded rock, but is not itself 
glaciated. It appears, however, from the fauna of the raised 
shell-banks of the country (as worked out by Sars and Kjerulf), 
in which recent shells do not rise above 380 feet, that the seas 
of the upper levels were still glacial; and, though the 
Trondhjem fjord was free from land-ice, other deeper fjords and 
higher coasts may still have had glaciers coming into conflict 
with the sea, and producing the glaciated rock-terraces described 
by Sexe. All the evidence obtained discountenances Sexe’s 
view that these rock-terraces were cut out by glaciers, as well 
as Carl Petersen’s that they were rasped out by floating ice 
coasting the shores. On the clay terraces coast-ice has left no 
more sign of its presence than the winter freezing of our British 
rivers leaves upon our river-terraces. (2) If the coun'ry was 
upraised by a succession of elevatory jerks, as supposed by most 
geologists from Keilhau downwards, most of these would seem 
to have been small—much smaller, at least, than is supposed by 
Kjerulf. It is improbable that even Leanzgen Bay was secluded 
enough to contain a record of all the oviginw coist-lines. The 
longer pauses and greater storms may have effaced an unknown 
number by a process of excision exemplified in all its stages by 
the map. It is hard to say, in fact, where the subdivision would 
end if all were preserved. The smaller terraces remind the eye 
of the incised lines and little planes engraved on the sandbanks 
bordering the rivers after a flood, in which case there is no 
periodicity in the subsidence of the waters, (3) The preserva- 
tion or excision of the terraces thus seems to depend as much 
upon local circumstances—exposure to storms, resistance of 
coast-line, &c.—as upon anything else. It is impossible at 
present to predicate which of them shall in any given place 
remain. Whether elevation by jerks, therefore, b> postulated 
or not, all hope of correlating these terraces throughout the 
country must be deferred until their heights have been accurately 
determined by level. The measurements hitherto made, not 
even excepting those of Profs. Kjerulf and Mohn, are probably 
inadequate for the purpose. This observation seems to apply 
also to the terraces graven in rock. In their aneroid measure- 
ments of the upper strand-line at Trondhjem these observers 
differ by 55 feet. (5) On entering the mouth of the Trondhjem 
Valley the terraces come under an influence other than that of 
the sea-waves. The valley was worked out, in deposits partly 
levelled out by the sea, according to the laws of river-terracing 
under the accelerating influences of a falling sea-level. The 
processes of automatic river-terracing are beautifully exemp- 
lified within the district mapped in the deep lobe-shaped 
curve of the river just before it enters the sea. The terraces 
have been added one after another to the point of the lobe of 
land thus surrounded, which is known as Oen. 
The Glacial Deposits of Montrose, by Dr. J. C. Howden. — 
These consist, in order of age—(1) a marine clay containing 
fossils of a purely Arctic type, apparently the bottom of a deep 
sea. Above this is seen the estuarine clay, beneath which, how- 
ever, are often found deposits of peat. Over the estuarine clay is 
a bed of stratified sand, and above that a dense non-fossiliferous 
Carse Clay, varying in thickness from 4 to 6 feet. The sequence 
of these deposits was held by the author to indicate interglacial 
periods. 
Trish Metamorphic Rocks, by G. H. Kinahan, M.R.1.A.— 
This paper is an epitome of what is known as to the age of the 
Irish Metamorphic rocks. 
Barium Sulphate as a Cementing Material in Sandstone, by 
Prof. Frank Clowes, D.Sc.—The author described the ‘‘ Hem- 
lock stone” and other similar blocks of Lower Keuper sandstone 
in the neighbourhood of Nottingham. They stand out in hard 
masses from the more easily denuded sandstone around them. 
Analysis has shown that the cementing material of the upper 
part is barium sulphate. This being practically insoluble with- 
stands denudation and protects the lower part from waste, this 
lower part being mainly cemented by calcareous matter. Bischof 
has proved the occurrence of barium sulphate as a cementing 
material in some foreign sandstones, but the fact is probably new 
in Britain. ia 
On Dep Borings at Chatham. A Contribution to the Deep 
seated Gelozy of the London Basin, by W. Whitaker, BAX, 
F.G.S., Assoc. Inst.C.E.—A few years ago the Admiralty made 
a boring in the Chatham Dockyard extension, to the depth of 
9033 feet, just reaching the Lower Greensand, and in 1883-84 
followed this by another boring near by. After passing through 
27 feet of Alluvium and Tertiary beds, 682 of chalk, and 193 
feet of Gault, the Lower Greensand was again reached ; but, on 
continuing the boring, was found to be only 41 feet thick, when 
it was succeeded by a stiff clay, which, from its fossils, is found 
to be Oxford clay, a formation not before known to occur in 
Kent. At its outcrop, about seven miles to the south, the 
Lower Greensand is 209 feet thick, aid is succeeded, a little 
further south, by the Weald Clay, there 600 feet thick. Not 
only, however, has this 600 feet of clay wholly disappeared, but 
also the whole of the next underlying set of deposits, the 
Hastings beds, which crop out everywhere from beneath the 
Weald Clay, and are also some hundreds of feet thick. More 
than this, the Purbeck Beds, which underlie the Hastings Beds 
near Battle, are absent, and also the Portlandian, Kimme- 
tidze Clay, Corallian, &c.; beds which have been proved 
above the Oxford Clay in the sub- Wealden Boring, to the great 
thickness of over 1600 feet. We are therefore faced with a 
great northerly thinning of the beds below the Gault, a fact 
agreeing in the main with the evidence given of late years by 
yarious deep wells in and near London. Three other deep 
borings have been mide or are being made near Chatham, all 
of which have passed through the Chalk into the Gault, and one 
has gainzd a supply from the sand beneath. The practical bearing 
of the Chatham sectioa is, however, to enforce the danger of 
counting on getting large supplies of water in the London Basin 
