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Proceedings of Indiana Academy of Science 



this response comes from a stimulus in the great morainic area of 

 Steuben County and vicinity. Figure 5 shows the general idea. It is 

 an interesting thing that artesian wells occur at many points between 

 Steuben and LaPorte Counties. At South Bend there is a lens of 

 impervious clay as shown in figure 5. A well drilled into the gravel 

 beneath this clay will overflow in the lowlands along the St. .Joseph 

 River while a well sunk into the gravel above the clay will not over- 

 flow. In other places in this vicinity the same condition exists. The 

 same influence communicated to the bottom of the lake system at La 

 Porte would influence its level. The position of these lakes at the edge 

 of the great clay deposits of the Kankakee lowland would account for 

 the hydrostatic head by which the lake level is sustained slightly above 

 this lowland. The response to the static influence from this great dis- 

 tance would lag far behind the stimulus. I know of no experiment or 

 investigation which has ever been made to determine the rate of re- 

 sponse of stimulus from hydrostatic head through rock. No conclusive 



Fiji. "). Cross-section profile from Lake MichiKan to Lake Erie showing major 

 ground movements as dominated by major relief features. 



statement as to the cause of the response shown in figure 3 can be 

 made, but as before stated the responses are too definite and persistent 

 to be ignored. 



Ajjparent Effect of Installation of Storm Sewage System in La- 

 Porte upon the Lakes, ivith Explanation. The storm sewage disposal 

 .system of LaPorte was constructed in 1912-13. The extent of the main 

 lines of this system is shown in figure 2. Laterals extend to all parts 

 of the city along these mains. All that part of the .system' north of 

 the junction of the Fifth Street main with the main sewer line is above 

 the level of Clear Lake. Following the in.stallation of this system there 

 has been a rapid decline in the level of the lake system. As previously 

 stated, Mr. W. A. Cummings, Park Superintendent, has determined this 

 c'ecline to have been about five and one-half feet, in eight years. Be- 

 cause of the coincidence of the beginning of the rapid decline of the 

 lake level with the installation of the sewage system it is apparent that 

 they are related. 



The soil underlying the city of LaPorte is principally sand and 

 gravel with small amounts of clay. Formerly much of the water which 



