SCIENCE 



NEW YOEK, DECEMBER 8. 1893. 



SOME GEOLOGICAL FEATURES OF JACKSON 

 PARK, CHICAGO. 



BY D. E. WILLAED, UNIVERSITY OP CHICAGO, CHICAGO, ILL. 



Visitors to the great Columbian Exposition during the 

 past season can hardly have failed to have been impressed 

 with the beauty and harmony of the landscape features of 

 Jackson Park. Those who have made toijography a study 

 must have found it a place of especial interest. 



Only when one compares the Jackson Park of 1893 with 

 that of former years can he realize the greatness of the 

 transformation, or comprehend the herculean task which 

 confronted the gardener in his attempt to bring beauty 

 and harmony out of this wild, and from an artistic stand- 

 point, chaotic region, or appreciate the magnificent success 

 with which the problem was finally solved and the wild 

 waste transformed into a place fit to be called the "Gar- 

 den of the Gods." 



The Jackson Park of former years, in large part a wild 

 and unimproved morass, a succession of sandy ridges 

 and low stretches of marsh, the resting place of water- 

 loving fowl during their season, and the resort of game- 

 loving marksmen, contrasted with that of 1893, with its 

 beautiful avenues, glittering lagoons and studded islands, 

 a dreamland of beautj' in its rare combination of nature 

 and art, surely presented a marvellous example of what 

 it is possible for the landscape gardener to accomplish. 



To understand the matter at all well, the topography 

 of the adjacent vicinity must be studied, which at once 

 introduces us to a very interesting geological problem. 



Along the borderland of Lake Michigan in the vicinity 

 of Jackson Park may be observed ridges running south- 

 ward and diverging from the lake shore, varying in width 

 from a few yards to a considerable fraction of a mile, and 

 in height from that which barely distinguishes ridge 

 from adjacent lowland to twenty feet or more; the front 

 edge, i. e., the eastern or one toward the lake, usually 

 being more or less abrupt, while that on the opposite side 

 not infrequently grades down to the adjacent marsh so 

 evenly as to make it difficult to determine where the ridge 

 ends and the marsh begins. 



If the observer traverses the lake shore southward he 

 finds these ridges occurring at irregular intervals, and if 

 he follow one of them along its course he will soon fiod 

 himself at considerable distance from the lake, and rido'es 

 rising to view both to the eastward and westward. 



Examination of their structure where exposed in cellars 

 or excavations for sewers, or perchance where a sand-23it 

 has been opened, reveals stratification and evidence of 

 distribution and deposition in water, with alternating lay- 

 ers of coarse and fine sand and gravel. 



The intervals between the ridges are marsh or lowland, 

 and during certain seasons of the year are often covered 

 with water. 



The ridges are easily recognized from a distance by the 

 oaks which usually' — and, so far as our observations have 

 extended, always — cover them in a state of nature, a sharj) 

 tree-line marking the transition from ridge to marsh. 



If from the roof of the Manufactures Building or 

 other elevated stand23oint the region south of the park be 

 surveyed, one observes that a broad level plain stretches 

 southward from the boundary of the park (Sixty-seventh 

 street), toward South Chicago, Pullman, and Lake Calu- 

 met, the eye being able to trace the landscajDe clearly as 

 far as about One Hundredth street. This region is seen 

 to be traversed in a generally north-south direction by 

 lines of trees, which, by closer observation, are found to 

 coincide with the sand ridges. 



Abutting against the southeast corner of the park there 

 is observed a grove of oaks of considerable extent con- 

 sisting of broader or narrower tree-covered belts (ridges), 

 separated by narrow strips of lowland (lagoons), while 

 toward the lake other tree-belts are noticed, separated 

 by low even tracts of marsh-land of varying width, en- 

 tirely destitute of trees. And again, for some miles to 

 the westward lines and jjatches of trees indicate ridges or 

 outliers, and a nearer apj)roach reveals some very high 

 and extensive ones. 



If the grove mentioned above be examined more close- 

 ly, it will be found to consist of a somewhat comjDlicated 

 series of ridges and lagoons. 



Near Seventieth street, the first ridge in the series 

 which we can study satisfactorily — some having been 

 destroyed by grading — to the east from Stony Island 

 avenue (which forms the western boundary of Jackson 

 Park) divides to the southward, and the intervening 

 lagoon' gradually widens. The ridge is quite pro- 

 nounced, especially as to its front, along east of the tracks 

 leading to the Terminal Station, and here again the sec- 

 ond lagoon, which forms the interval between the first 

 and second ridges north of Seventieth street, becomes nar- 

 rower and j)resumably disajspeared a short distance fur- 

 ther north in the park. This second ridge is quite regu- 

 lar in outline, and transversely symmetrical. It has to a 

 striking degree the appearance of an old-fashioned coun- 

 tiy 'turnpike" road before it has been distorted by heavy 

 wagons. It is as evenly built as a gardener could have 

 made it with his shovel and rake, rising gradually and 

 evenly to a height of about four and a half feet, and then 

 as evenly, though slightly more abruptly, descending to 

 the lowland on the east or lake ward side. It is about 

 eight rods in width at Sixty-ninth street, two blocks 

 south of the jjark fence, and is separated from the next 

 ridge by a lowland belt at this point, about four rods in 

 width, which, however, gradually widens southward, and 

 narrows northward till it disajspears, and the two ridges 

 unite just south of the park limits. The highest point of 

 the combined ridge, just above the juncture of the two ad- 

 jacent edges, is about six feet. 



Eastward again of this third ridge or eastern arm of 

 the second (which is about twenty-five rods in width) ex- 

 tends a broad level tract of lowland of a breadth of a 

 hundred rods, covered with a growth of rushes and other 

 marsh plants, and so low that it is covered with water 

 during the wet seasons of the year and furnishes a favor- 

 able haunt for wild fowl and a tempting field to the 

 sjjortsman. Still further east is a broad ridge sagging 



'The terms lagoon, lowland, and marsh-belt are used interchangeably 

 throughout this discussion, for the low interval which separates the ridges, 

 whether or nut it be covered all or any part of the year with water. 



