298 



O.N Till'] I'EUIODICAL RISE AND FALL OF THE LAKES. 



[1854. 



Professor Hull was well Boconded bj Professor Mather, after- 

 wards chief director of the Geological Survey of Ohio, and sub- 



Bequciitly (in 1 K I /», -Id, and 17) a rcsidcn tin- shores of Lako 



Superior, observant of the meteorology and change of level of 

 thai Lake, from whose reports and other writings I extract the 

 following hurriedly condensed particulars respecting Lakes Erie 



and .Superior:* 



"A tradition exists that there is a periodical rise and fall in 

 Lake Erie, through a certain number of years. If it is true— 

 and there are reasons for believing that it may be so, to a certain 

 extent — it is evident that the present rise (1838) is higher than 

 has occurred for many years before, for extensive tracts of forest 

 are now overflowed, and timber killed in consequence, the trees 

 of which indicate a long period of growth. The causes that may 

 concur to produce such a variation in the level of the Lake are: 

 — 1st, An obstruction to the drainage to the usual quantity of 

 water, in cousequence of which, if the usual supply continues, the 

 water must rise. 2d, The increased or diminished supply of 

 water, dependent on the wetness or dryness of the season, the 

 relative temperature, and amount of evaporatio^both from the 

 surface of the Lake and the country which receives its drainage 

 waters, and the amount of water supplied by the Lakes above, 

 as Lakes Huron, Michigan, and Superior, — the amount of water 

 contributed by which is due to the same general causes, with 

 the possible addition of an increasing water-way from the cutting 

 down of their outlets, and pouring down an additional supply. 

 3d, Another possible cause may be taken into account in the 

 varying level (or upheaval) of the solid earth itself — examples 

 of which are mentioned in various works on geology, as to be 

 seen in part of the coast of Sweden, where it is said to be slowly 

 rising at the present time." 



To this the Professor well adds : — " It is considered an object 

 of great importance to determine what are the causes of this 

 effect ; and it was therefore intended, if the Legislature had made 

 an appropriation corresponding to the estimate, and with provi- 

 sions to the Bill which was reported last Session, to have set in 

 train a series of observations in several localities on the Lake 

 coast, and in different parts of the States, so that by the period 

 for the close of the survey, a determination of the causes of the 

 rise and fall of the Lake may have been attained. All the aid 

 which the various branches of meteorology could have secured 

 would also have decided the question as to the small tides, which 

 are said to be very sensible in some places." 



To the foregoing remarks of Professor Mather, I may be per- 

 mitted to add that it is much to be regretted that any circum- 

 stances should have prevented his excellent suggestion from being 

 carried into effect; but that such having unfortunately been the 

 case, it now remains for the British province of Canada to have 

 the credit of completing so desirable a work, on a far more ex- 

 tended scale. 



Turning again to Lake Superior, I am happy to be able to 

 quote the following (abridged) remarks by the same writer :f 



" The great rise and fall of the level of the waters of the great 

 Lakes, through a series of years has been long noticed. The 

 cause is doubtless due to a greater quantity of snow and rain, 

 or of a lower mean temperature and diminished evaporation 

 during the period of rise, and the reverse during the time of fall 

 of the water-level. During 1838-30, the waters were higher 



* See Geological Report of Professor Mather for 1838. 

 f See Report of Geological Survey of Ohio for 183S-39 ; and an 

 article in the American Journal of Science for July, 1S48. 



than they had been before for at least two centuries. This is 

 demonstrated by the large tracts of land that were inundated 



which were covered with forest trees, many of them the growth 

 i i age The e trees were di troyed by the overflow round 

 Lakes Erie and Huron, and on the Sle. Mario river, between 

 Pbinl Detour andtheSault Ste. Marie. 



" We have no accounts of Lake Superior at that time; but 

 there are facts that indicate a marked variation within a few 

 years. In 1 :- 145 a rock in the middle of the entrance of Eagle 

 Harbour, showed itself only in the trough' if the waves; and the 

 narrow outlet between the west end of Porter's Island and the 

 mainland at Copper Harbour, was of such depth that loaded 

 boats could enter without touching the rocks. In 18 10, the 

 rock at the mouth of Eagle Harbour was one-and-a half feet 

 above water; and boats could not get into Copper Harbour. 

 In June, 1817, the rock above-mentioned was still more above 

 water, and the outlet to Copper Harbour could be crossed by 

 stepping on the projecting points of the ieef, without wetting 

 the feet; and during some depressions of the water by barome- 

 trical waves, it was laid almost entirely dry. Emm the 18th of 

 June to the Cth of September there was a rise of full twelve 

 inches. It has been observed on this Lake that the water is 

 lowest in spring and highest in autumn. This is readily ex- 

 plained by the fact that in winter most of the ordinary supplies 

 of water from the drainage of the surrounding country are cut 

 off, by being converted into ice and snow; while evaporation 

 from the surface of the Lake by the dry northern winds conti- 

 nues to carry away a very sensible quantity of water. During 

 the spring, on the contrary, the snow and ice melt, and the accu- 

 mulated stores of winter flow into the Lake in greater quantity 

 than to compensate for the evaporation and the drainage at the 

 outlet. . . During a century past the waters of Lake Supe- 

 rior cannot have been more than four feet above the level of 

 1S47, for any considerable time, as is evident by the growth of 

 trees of two feet in diameter at Porter's Island, which would 

 have died had the ground around them been inundated for any 

 great length of time." 



To descend once more to Lake Erie. I am next indebted to 

 Colonel Whittlesley, Topographer to the Geological Survey of 

 Ohio for the following, confined to the annual and daily fluctua- 

 tions in that Lake, with a variety of other acceptable details re- 

 specting particular sudden floods, as well as for a concise but im- 

 perfect tabular view of the reported, combined with the known 

 annual variations in the level of its waters from 1790 to 1838. J 



" The general belief amongst navigators and residents on the 

 Lakes appears to be uniform against the existence of any law by 

 which these fluctuations are governed or may be predicted. The 

 scanty information collected tends to the conclusion that these 

 general elevations and depressions are fortuitous, and the result 

 of accidental disorder in the seasons throughout the Lake coun- 

 try. It is, however, well established that there is in Lake Erie an 

 annual tide, independent of the general stateg of the water, which 

 rises from eight to fifteen inches in the mean. The minimum 

 occurs about the time of the breaking up of the ice, late in win- 

 ter, and the maximum late in spring or early in summer and 

 fall. In the winter less change is perceptible; but early in 

 spring it rises very fast, and with great regularity, till it reaches 

 the maximum. All measurements should be taken subject to 

 this change; but I am unable to fix a mean surface fur the year, 



% See Colonel Whittlcsley's Report for 1S38-39. 



2 Stage is the word used, meaning "level," I presume. — R. L. 



