In the summertime the melting back was greater than the forward movement and the lobe would recede. In the winter time it would push forward again; so back and forth it went for many, many years.
As it came down from the Hudson Bay country it gathered up and pushed along great masses of earth, stone, boulders, gravel and sand, and as its southern edge melted it deposited this conglomerate mass of materials and formed what is known by geologists as the Valparaiso moraine. This moraine extends from northwest of Chicago, completely around the southern end of the lake and up into Michigan northeast of Michigan City. It is known as the Valparaiso moraine because the city of Valparaiso, Indiana, is located near its southern crest. This moraine is in some places three hundred feet high and from eight to twenty miles wide.
When the great ice bergs had receded some distance north of the moraine it left a lake between the ice and the moraine, which kept growing as the ice receded. This lake is now known as Lake Chicago. Lake Chicago found its outlet through the sag southwest of Chicago.
Its first shore line was about sixty feet above the present level of the lake and may easily be traced along the moraine by the results of the action of its waters upon the moraine deposits and the sand and gravel deposits along its shore.
This old beach is called the Glenwood beach, because the village of Glenwood, Illinois, is located upon it at a point where it is well defined. This shore line enters the state of Indiana at Dyer and extends easterly to about a mile north of Merrillville, eight miles south of the Grand Calumet river, then easterly to one-half mile north of Ainsworth and then northeasterly to a point about one mile southwest of McCool, then south three miles, then easterly two miles, thence northeasterly to a point one mile south of Chesterton, and then easterly from a mile to one-half mile south of the present Little Calumet river to the Laporte county line; thence west from a mile to one-half mile north of said river to a point two miles east of Dune park, thence northeasterly and from two to two and one-half miles from the present lake shore around Michigan City and up into Michigan.
After Lake Michigan had remained at this level for a long time it suddenly fell about twenty feet and there remained for another long period. This second beach is what is known as the Calumet beach, and is so called because it parallels the Little Calumet river about a mile south thereof from Thornton, Ill., to a point east of Dune park where it touches the Old Glenwood beach.
It passes through Lansing, Ill., Highland, Liverpool and Baileytown in Indiana and upon and along this beach what is known as the Ridge Road runs.
Again the Chicago lake fell about twenty feet to what is known as the Tolleston beach, so called because the town of Tolleston, now a part of Gary, is located upon it. It entered our state south of Hammond, extended easterly through Hessville, Tolleston, Miller, Dune park and thence on easterly about a mile north of the Calumet beach, and from one-half to three-fourths of a mile from the present lake shore.
After a long time the lake again fell about twenty feet to about its present level.
The great glacier above referred to rested upon the solid rock, and as it moved southward leveled hills, dug out great valleys, pushed and carried forward great masses of earth, rock, bolders, gravel and sand, as above stated. In its movement, it ground and scoured the bed rock with ice and with the sand, gravel, boulders and rock held in its mighty grasp with an inconceivable force, producing rock or boulder dust from which clay is made, sands and gravel. Most of the rock or boulder dust, being exceedingly fine, was carried away in the current through the sag and down to the gulf. Some of it, however, found quiet nooks and settled, forming our clay deposits. Much of the sand and gravel remained in the lake or along the shore.
The dunes created by the Tolleston beach and the sands washed up by the present lake, constitute all the dunes north of the Little Calumet river and the long narrow marsh that extends from Baileytown easterly to Michigan City, and constitute what is generally understood when one now speaks of the dunes.
This dunes belt is from one to three miles wide and from a few feet to one hundred and ninety feet high.
The first ridge along the water edge extends from the Gary mills in an almost unbroken line to New Buffalo, Mich. Back of the first ridge the ridges vary in direction and enclose innumerable little valleys, which are from twenty to fifty feet above the level of the lake and contain from a few square rods to three hundred acres in area.
The dunes are with few exceptions covered with a great variety of trees, shrubs, vines, ferns, mosses, lichens and grasses and the little ponds and lakes which they sometimes enclose add another great variety of vegetation. This great variety of vegetation is accounted for, by the belief, that before the last great glacial period, there was a period of high temperature in this latitude and that southern vegetation had migrated far to the north and occupied this territory at the time of the glaciers and was not wholly destroyed by that period; that when the ice sheets came down from the north bearing its burden of earth and soil, it brought the northern plants with it and left them here where they still remain. And even now all the great rivers of the north bear the roots and seeds of north vegetation into the lake, where they are carried southward by the current that flows along the western coast or upon the ice that the northern winds bring down and pile high along the southern shore every winter and spring.
Here they are scattered by the waves and the wind and find along the shore, upon the dunes, in the valleys, ponds and little lakes, moisture, soil and climate to suit their varied likings.
The current that comes in along the western coast of Lake Michigan washes away the western shore and carries it along to where the current strikes the southern shore at a point near Mount Tom, where it and the other wash of the lake is thrown up by the waves, dried by the sun and blown by the winds into dunes of every shape, form and size. Here upon the southeasterly shore of Lake Michigan are the greatest dunes anywhere to be found along the shore of the Great Lakes.
Mount Tom, located immediately upon the waters edge, is one hundred and ninety feet high. It is almost due north of Porter and Chesterton in latitude forty-one degrees and forty minutes north and longitude seventy-eight degrees and three minutes west and covers more than one hundred acres; near it are many other dunes almost equal in height and area. At many places along the lake dunes are now being made, sometimes growing many feet in height and greatly in width in one year, covering up great growing trees, and at other places they are being blown away, uncovering trees that have been buried for centuries.
A bunch of coarse "sand grass" that flourishes upon the highest and driest dunes, or a clump of "sand willows" that grows everywhere, regardless of moisture or soil, or an old tree top, anything that will check the winds and hold the sand may start and build a dune. The grass and willows follow the dune up and on until its very height itself, checks and eventually stops its growth; then the great variety of dunes vegetation covers it over and preserves it for a while; eventually a place made bare by the uprooting of a tree, a snow slide or the burrowing of some wild animal will start a "blow out," which may increase until the whole dune is destroyed; but usually the tree felled by the sand being blown away from their roots form a new lodging place for other sands and the "blow-out" may in time be completely filled up and covered anew with vegetation.
A great pit, of many thousand cubic yards, has recently been excavated by the winds near the top of Mount Tom and may if not checked continue to grow until the whole mountain is removed.
An hour's work or two by some one would check the threatened destruction and with a little care the entire pit might be refilled.
The standard low water in Lake Michigan fixed by the United States government, as a basis from which all government surveys of the lake and surrounding country are made, is 578.5 feet above mean tide (sea level) at New York.
The standard high water in Lake Michigan in 1838 was 584.69 and the Chicago City datum was fixed at 4.75 feet below this or at 479.94 above sea level.
Return to main Gary Dune Park Post page.
Return to top of page.
Posted 29th June, 1999; updated 5th July, 2001.This page is at http://www.calumet.tripod.com/dunes/a-knotts.html.