LETTER FROM DR. SCHETELIO, PROFESSOR OF GEOLOGY AT THE UNIVERSITY AT CHRISTIANIA, TO DR. JOHAN HJORT,
APPENDED TO PRECEDING MEMORANDUM.
Professor Johan Hjort,
DEAR PROFESSOR HJORT,
I have duly received the documents and charts concerning the Hamilton Inlet of the Labrador Coast and have considered the question which you have placed before me, if the meteorological and topographical conditions of the Hamilton Inlet and Lake Melville have remained unaltered as they are now during the last 150 or 200 years, or more definitely since the year 1763.
There are no reasons for believing that the meteorological conditions have been characterized by less rainfall in this period. On the contrary the great progress of the glaciers of Norway during the eighteenth century indicate that the humidity was greater in this century and that therefore the supply of fresh water by the large rivers, which end in Lake Melville, was larger at that time than it is now, which tends to show that the fjord system of the Hamilton Inlet was then even less favourable for cod than it is now.
The other and still more important factor for a change of the hydro-graphical conditions are the oscillations in the bottom of the sea. If the Labrador coast during the last 150 or 200 years had undergone an uprise of considerable dimensions this might have influenced the hydrographical conditions considerably.
At “ the Narrows,” the entrance to Lake Melville, the hills on the Southern side have marked terraces of a height of 150 feet above the present water level. Further in towards Southwest in the Hamilton river valley marine terraces have been found in a height of some 300 feet above the sea. If the depths in the narrow entrance (the Narrows) which now are 10 fathoms only, were increased by 150 feet (say 25 fathoms) this would of course also lead to a widening of the entrance and to a considerable increase of the salt water flowing into Lake Melville.
For the consideration of this problem it is first of all of importance to remember the great similarity between the post-glacial history on both sides of the Atlantic in the two areas Fennoscandia and the Labrador territory.
The events in these two areas seem to have been synchronous since the late glacial period.
The Labrador district formed a definite and separate glacial area. During the last glacial period, which in America is called the “Wisconsin” period and in Europe the “ Mecklenburgian,” there was a narrow strip along the coast free of ice along the North coast of Labrador and along the west coast of Norway.
At the end of this period there appear in both these areas the late glacial submergence illustrated on the two appended charts of the “ isobases,” which are drawn from the investigations of the celebrated Swedish professor G. de Geer, who investigated the areas of Scandinavia as well as of North America. In both areas he found a perfect similarity, a larger submergence in the centre of the area and a smaller submergence towards the coasts. It is now generally accepted that the explanation of this submergence is to be sought in an isostatic movement due to the pressure of the ice. As far as Scandinavia is concerned the maximal submergence coincides with the final melting of the ice.
In the postglacial time an emergence or uplift takes place in both the submerged areas leading to the old position of equilibrium, and the uplift increases from the coast towards the Central areas.
For Norway Professor W. C. Brogger has proved that the uplift of South eastern Norway had already come to the present stationary position during the bronze age, i.e., that the relation between the sea and the land in South eastern Norway has been unaltered during the last 2,500 years. The marine limit is at the town of Christiania at 220 meter and at the mouth of the Christiania fjord at ca. 150 meter above the sea.
In the central parts of Fennoscandia this is somewhat different, the uplift here has not ended yet. Around the Gulf of Bothnia (a part of the Baltic) the maximum upheaval of the coast line is one centimeter a year or one meter a century. Since the year 1750 the coast line of the Gulf of Bothnia has therefore been lifted 1.7 meter. The uplift is therefore very slow.
For the Canadian area it may be stated generally on the analogy of the events in the Fennoscandian area that the uplift took place at a greater speed in the beginning of the post-glacial period than in the later part, that the uplift has been decreasing and that it now is very near the stable state of equilibrium.
My knowledge of the Canadian literature on the subject may not be complete. For the West coast of Labrador towards the Hudson Bay, Tyrrell (American Journal of Science Ser. 4 Vol. II. 1896) states as follows : “ The postglacial uplift . . . of the shore of Hudson Bay has virtually ceased, and . . . the land has now reached a stable condition.” Referring to the Northern part of the U.S.A. Davis (Physical Geography, 1900) states that the coast of Massachusetts and New Jersey in our time is sinking one or two feet a century. Spencer gives the same statement for the Northern part of the Eastern coast of the States which “ is now sinking at the rate of two feet a century.” (American Journal of Sc. Vo. 19, 1905.)
The conclusion from these statements seems to be that the peripheral parts of the Canadian area have come to rest, that the uplift is ended and that the neighbouring districts outside the area are found to be sinking very slowly.
The Hamilton Inlet belongs to what is here called the periphery of the Canadian area of glacial submergence. Marine terraces at the height of 150 feet are found at the entrance to Lake Melville and at the height of 300 feet in the Hamilton River Valley. It is very likely that the coast here has long ago been lifted to the stable equilibrium like the Labrador coast bordering the Hudson Bay, since both coasts have the same distance from the central part, which has been lifted to the greatest height.
Moreover it must be concluded that even if we accept an uplift as great as that now taking place in the Gulf of Bothnia—i.e., 1 cm. a year- we cannot even then consider the uplift to exceed one meter and seventy centimeters or approximately one English fathom for the time since the year 1750. Even this uplift, which in itself is very unlikely, would thus not have reduced the depths of the entrance to the Lake Melville, more than by one fathom in the time from the year 1750 to the present day, and such a difference in the topographical conditions can in no way have altered the hydrographical conditions of the fjord to any appreciable extent.
Christiania, 15th November, 1922.