Fisheries Research Board of Canada
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FISHERIES RESEARCH BOARD OF CANADA MANUSCRI PT REPORT SERIES (OCEANOGRAPHIC and LIMNOLOGICAL) No. TITLE E DISCOLOURATION OF FOXE BASIN ICE AUTHORSHIP N. J. Campbell and A. E. Collin. Establishment ATLANTIC OCEANOGRAPHIC GROUP Date d December 9, 157. Programmed by THE CANADIAN JOINT COMMITTEE ON OCEANOGRAPHY The Dis colouration of Foxe Basin Ice by N . J. Campbell and A. E. Collin. INTRODUCTION Foxe Basin is loc aced within the southern limits of the Canadian Arctic archip elago almost bordering on Hudson Bay (Fig. 1). The Basin i s bounded to the north and east by Baffin Island and to the west by Melville Peninsula and Southampton Island (Fig. 2). Acce ss to the ocean is through Foxe Channel and Hudson strait in t he south. At the northern end, Fury and Hecla Strait provides a passage from Foxe Basin to the Gulf of Boothia, Prince Regent Inlet and Lancaster Sound. The Basin is a shallow inland se a of 65 9 000 sq. miles completely sur- rounded by Precambrian and Palaeozoic rock formations of granite and sedimentary deposi ts. This depression appears to be a sub. merged continuation of the Palaeozoic regions around the eastern and western perimeters The sea ice condi tion of Foxe Basin is a unique feature in the Canadian Arctic di 3tinguishable from nearly all other types of ice by its remarkab Le colour. This ice is characterized by a uniform brown or buf --coloured layer of sediment which per- ennially appears on the) surface of the winter floes. The unusual condi ;ion of this ice was first noted in 1615 by William Baffin who described his impressions of the soiled and stained ice of thi 3 region (Markham, 1881). Later in 1631, Luke Foxe encountered the same type of brownish coloured ice in - 2 his explorations of Foxe Basin. The term "foxy ice" which is commonly used today to describe the dirty ice, is believed to have originated in Foxes diary, but a typographical error in the marginal notes of his published account obscures positive identification of this interesting historical fact (Foxe, 1635). Since these two early expeditions, almost every ship which has visited Foxe Basin or Foxe Channel has reported a similar dirty state of the ice (Drage, 1748; Parry, 1824; L . yon, 1825; and "'akeham, 1898). Much speculation has arisen regarding th e origin of the dirt and its composition but few theories have accounted for all the facts. Baffin believed the ice to ha' ve formed near shore, but A. P. Low and R. Bell, two geologi sts who worked extensively in Hudson Strait, surmised that t he dirt was air- borne (Low, 1906; and Bell, 1885). This conc lusion was based on the widespread distribution of the dirty i ce. Sir W. Parry, however, was a little more cautious in his explanation of the dirty ice despite the fact he spent two winte rs in Foxe Basin. Parry, (1824), states in his journal "How the se substances had been brought here in such abundance another y ears' experience the phenomena of these seas had not taught us to explain and before we left this coast, we saw many hundred square miles of ice thus covered." Recent Observations. In 1955 and 1956, the Atlantic Oceanogra phic Group undertook an oceanographic survey of Foxe Basin on boar d H.M. C. S. " Labrador? -3 - As part of this surve y the origin of the dirty ice was re- considered in view of the many conflicting theories. These theories give conside ration to air deposition of dirt or pollen, plankton grow th, grounding of ice and fluvial de- position (Kindle , 192 4; and Kiernan, 1957). From the results of the 1955 cruise, i t became apparent that none of the above theories fully accoun ted for all the characteristics of the ice, and the only exp lanations that showed promise stemmed from the oceanographi c and geological conditions of the Basin. The circulation of Foxe Basin is dominated by a southerly flow along the wester n side and a counterclockwise gyral in the central area sout h of Prince Charles Island. The north- south exchange of wat er through Foxe Channel maintains the counterclockwise swee p of the currents in the Basin and the movement of water and ice into Hudson Strait (Campbell and Collin, 1956). It is the latter discharge of ice into Hudson Strait that introduce s the dirty ice into the Hudson Strait pack and finally the Labrador coast pack ice. The summer and w inter meteorological conditions are mark- edly different as evi denced by ice and snow cover. In the winter the whole area is cov ered with severly hummocked ice, while in late summer, August a nd September, the ice generally disappears either by melting or transport to Hudson Bay or Hudson Strait. The dirty ice pr esents several features which are unusual, the most obvious bein g its distribution throughout all of Foxe Basin and most of Fox e Channel during the ice season. In fact, )k it is a rare occasion when one encounters clean ice. The clean ice floes are so cont rasting in shape and colour that they appear to invade the Basin t hrough Fury and Hecla Strait, or form in - 4 - wh sheltered bays. In contrast, the dirty ice i s nearly always hummocked, rafted, and well broken up into small sand medium tr floes (Fig. 3). The general physical charact eristics, shape and topography are much the same as old polar ice which has Th weathered after several seasons in the Arctic Basin. The ap: roughness and uneven topography of the ice ha s been claimed Th( by some authorities to be the most severe in the Canadian sc Arctic. This characteristic is believed to b e a phenomenon pal closely associated with the discolouration. on The material found on the ice is of an o live brown or buff shade, and is fine textured. The size 1 imits vary on the or average from 0.005 mm. to 0.5 mm. On the Mun sel colour code, the dry colour falls in the yellow hue with a light value and or chroma of 4Y7/1. wet The dirt deposits are uniformly distributed over the surface (Fig. 4). The ice presents such an appearance that it cannot be of mistaken for ice that has grounded or overturned in shallow water upo and become strewn with debris such as weeds, rocks and mud. For ina comparison, the sparklingly clean floes that one usually encounters thi off the Baffin Island coast are illustrated in Figure 5. Two other illustrations (Figs. 6 and 7) are given of ice-borne sediments, gravel and rockfalls on ice, and an iceberg strewn with coarse to gravel and stones. difJ Mechanisms of transfer of ice-borne sediments. els(' The unique features of the dirty ice are its perennial occur- Bay rence and distribution. The area of coverage is of the order of of 50,000 to 60,000 sq. miles each ice season. The regular appearance of this sediment bearing ice suggests a permanence in the forces - 5 - which bring about this unusual state. The vprious sources and boundary processes involved in the transfer of ice -borne sediments, are summarized in Table I. Most of these phenomena are described in detail by Kindle (1924). The restricted geographic location, type of dirt, and perennial appearance, eliminate most of the listed factors as possibilities. The only mechanisms that can satisfy, the requirement of large scale distribution of dirt are plankton, meteoric dust, wind-borne particles and bottom sediments. Laboratory analyses of the de- posits further limit the field of contributory causes. Microscopic and x-ray analyses reveal that the constituents of the dirt are inorganic and mineral. The floe muds are quantitat- ively heterogeneous in minerology and size fractions. Particles of illite, quartz, biotite and calcite are common and these as well as others appear fresh and unaltered chemically. Wind deposition has been considered as the most likely source of the dirt and the argument in favour of, this hypothesis is based r upon the fineness of the sediment and the large area of contam- ination (Low, 1906; and Kindle, 1924). However, At is felt that ere this theory leaves much to be desired in view of recent inves- tigations. .ents, I Proponents of the wind theory consider two aspects related to the seasonal per _ods of snow cover. In either case, it 14 difficult to conceive that wind deposition of dirt would not occur elsewhere, for example, the Gulf of Boothia, Committee Bay, Hudson r - Bay or Hudson Strait. It would be expected that under conditions of wind deposition, the semi-permanent ice in Committee Bay would nee - 6 - be similar in appearance to that of Foxe Basin To account for a winter formation of dirty ice in Foxe Basin, a large portion of the immediately surrounding terrain must remai n bare, even with an average snowfall of 60 inches. Under these conditions, the wind could conceivably remove the fine particl es of sand, silt and clay and deposit the material over the ice in the Basin. Evidence to support this view should be found on the sea ice and land snow, Wind deposition of dirt is periodic, depe nding on the fre- quency and strength of the winds. This effect results in banding of dirt layers in ice, and also on land snow. No evidence of banded layers of dirt have been observed with the Fox e Basin ice and further, no accounts of discoloured snow eithe r on the land or islands have been described by expeditions tha t have wintered in the Be si no The above arguments, however, are answere d by assuming that the dirt is laid down in the spring when the s now cover has die- appeared from the land.