154 GEOLOGY OF EASTERN WISCONSIN. 



there lies a ledge of IS'iagara limestone, underlaid by impervious shale 

 from the surface of which issue frequent springs. The clay deposits 

 of the basin, in which the city lies, abut against and overlap this shale. 

 The junction is in all probablility permeable to water, which would 

 thus reach the porous strata of sand and gravel that are found within 

 the blue clay. That this is the true explanation of the Artesian wells 

 of Taycheedah and Byron is more than probable. To the west, the blue 

 clay rises to the surface and lies upon, or graduates into, the more 

 gravelly drift hills of that region, and may not improbably derive its 

 water supply from thence. 



The fountain heads of the second and third classes, viz. : those that 

 rise from the concrete and from the limestone, are doubtless the §ame, 

 or at least their fountain heads are associated, except perhaps those of 

 the deep wells, whose reservoir is more distant; in all cases it is 

 probably to the westward. Lamartine and adjoining townships furn- 

 ish favorable conditions. The surface of the rock, as well as its lay- 

 ers, rise in that direction. The slight local exception to this in the 

 western portion of the city is not sufficient to afiect the general prob- 

 lem. The rock ajjpears at the surface to the southwest, along Seven 

 Mile creek, at an elevation of 122 feet above Lake "Winnebago. The 

 general surface of tlie town of Lamartine is about 150 feet above Lake 

 Winnebago, if a single series of aneroid measurements is to be trusted, 

 and consists of low hills and ridges interspersed with marshes. The 

 surface drainage is very imperfect. The hills and ridges- are com- 

 posed of the varying mixed material of the unassorted drift, and are 

 more or less permeable to water. 



Phenomena connected with the boring of wells in this region show 

 that certain of the layers of the underlying magnesian limestone are 

 practically impervious to water, while others are not. These with the 

 clay above furnish the necessary pervious and impervious strata, and 

 complete the requisite conditions. 



The fountain head of Mr. "Wild's well is to be found along the line 

 of outcrop of the St. Peters sandstone within which its reservoir un- 

 doubtedly lies. Near Eipon, the St. Peters sandstone outcrops at an 

 elevation of about 325 feet above Lake Michigan, or about 150 feet 

 above the surface of the well, thus giving an abundant elevation. 



The flowing wells of Taycheedah are from 60 to 70 feet deep, but 

 do not reach the rock. It seems most probable that they derive their 

 flow from veins having their origin at the surface of the shale beneath 

 the ledge, as already explained, and as shown in the sections. The 

 water in some of the wells is highly impregnated with sulphuretted 

 hydrogen. 



