The daily morning journal and courier., 1899-06-05
CHICAGO IS BEING ENGULFED
GRADUAL TTLTING OFTBE EdRTIE,S s
 CRUST IN NLAKEEEGIoN.

Suggestive Geological Discoveries
 Predictions of Waters Emcroa chment
 Professor c. K. Gilbert contributes tc the latest volume of the geological sur. vey reports some interesting revelations about actual and possible changes oi level in the fake region of this coun- try. Attention was first directed to this matter in 1869, when Wisconsin sur Veyor noted that mill-race at the east ern end of Lake Superior was dry, while there were evidences that along the southern and western shores of that body of water the streams at their moLths seemed to be little fuller than ever. The phenomenon could be best explained not by drouth thet would affect the whole lake surface alike, but by general changes In the relative height of the different districts.
 A notion of this sort has the partial corroboration of history. The geologists on tracing the outlines of the Great Lakes as they existed shortly after the glacial period, and comparing these with the present configuration of the inland ocdS, tIG dDlC lO uGlGCl illdIh6u ullLSl ences. Moreover they can see that the terraces" left by subsiding waters around Lake Ontario are about $50 feet higher at the extreme northeastern end than down at Hamilton and Lewiston Similar evidence indicates that, as com pared with the level at Chicago, the re- zion lying a little to the northeastward of the Georgian bay in Canada has risen 250 feet.
 Scrutiny of various reports that have been made independently of one an- other brings to light the fact that most of the streams which run into Lakes Ontario and Erie along the western half of the south shore possess certain traits in common. Well inland they follow a fairly steep grade and have corre- spending swift movement On approach ing the large bodies of water into which they empty, they become sluggish, hav- ing been submerged. This fact corrob- crates the testimony just referred to, but without proving that any change of level is now in progress A fresh in vestigation was needed for the latter purpose.
 Professor Gilbert has succeeded in en- listing cooperation which has enabled him to find out what has taken place during the last thirty or forty years. Four pairs of stations were taken into consideration, each pair being so made up as to combine points lying on gen. erally northeast -and-southWest line. These pairs included Sacketts Harbor and Charlotte on Lake Ontario, Port Colborne and Cleveland on Lake Erie, Port Austin and Milwaukee for the Hu- ron-Michigan basin, and Escanaba and Milwaukee for Lake Michigan alone Official records of water levels at these points were consulted. In some cases it was possible to find trustworthy data for a period of nearly forty years; in other for only twenty.
 The results attained were as follows: Relatively to Sackett's Harbor, Char lotte sank 0.061 foot in twenty-two years. This Is trif1e under three quar- ters of an inch. The places are ninety miles apart. Cleveland, relatively to Port Colborne, 16O miles away, sank ? 7S inches in thirty-seven years. Mill waulzee, as compared with Port Austin, 250 miles off, sank 0.13S foot (1.646 inch es) in twenty years. Thus Professor Gilbert is led to conclude that, along N iiiiC luHiiiilS At dtSl lteS west Ol SOuln- ward, there is mean subsistence taking place now amounting to 042 foot for every hundred miles. Eventually, it is hoped, more. elaborate measurements may be made, and more accurate con- clusions derived from the observations. But as the matter now stands, Professor Gilbert is disposed to take this view.
 The northern and eastern shores of all the lakes are rising, or else the south ern and western shores are falling. Pos- sibly both phnomena are occurring. In Lakes Erie and Ontario the general level is slowly rising, and this is most notice able in Port Dalhousie and Hamilton, where 1t amounts to six inches a cen tury. All ovar Lake Huron the water Is falling. most oonspicuously at the north and northeast. Mackinac the rate is six inches and at the mouth as the French river ten inches q century. At Duluth | the water is rising six inches, at Mil | waukee five or six inches. and at Chi | caso nine or ten inches. Inasnluch as Duluth Is built upon steep hils''o', she | can creep up out of the wat, 'rien- | ever required to do 80. But as Chicago | ig built on low ground, 1t is difficult to ! forecast her fate. The marine Dsur- ance companies would hardly like to | take any risks on her, The ground that divides the drainage | system of tho Illinois river and conse~ l quentiy the Mississippi from Lake l Michigan is cut by the former stream | to depth that leaves difference be- | tween the channel and the lake or only | eight feet. If TO new barrier were erect | ed. and if Lake Michigan rose at a per- fectly uniform rate at Chicago, it would | be about one thousand years before the lake would flow over the existing nat ural dam into the Mississippi. But, owing to differences in rainfall, similar Inequalities in evaporation, the direction of wind and their causes, the lake is much higher at one time than another. Professor Gilbert says:
 'Evidently the first water to overflow will be that of some high stage of the lake, and the discharge may at first be intermittent. Such high-water dis charge will occur in five hundred or six hundred years. After 1,500 years there will be no interruption. In about two thousand years the Illinois and Niagara rivers will carry equal portions of the surplus water of the Great Lakes. Tn 2,5O0 years the discharge of the Niagara will be intermittent, falling at low