ARTESIAN WELLS. 463 



of it, except at Milwaukie, where it appears to thin out on the south. I noticed in 

 all the brick-kilns that the arch-brick, and those adjacent, which were very hard 

 burnt, took the dull-white or cream-colour of the Milwaukie brick, but not with as 

 clear and pure a tint.* The iron contained in the clay collects in black, vitrified, 

 irregular spots or blotches, leaving the remainder of the brick of a whitish colour. 

 Those not so severely heated retain a fair red colour. The famous Milwaukie 

 brick are made from another deposit, also containing iron, but in a different form, 

 which separates by heat in the same manner, but with much less intensity, so that 

 almost all the bricks of the kiln are white. 



The red clay of Lake Michigan differs from that of Lake Superior in being more 

 ductile and tough, in not being marly, and it seldom has interstratified beds of 

 gravel, being homogeneous and persistent. At Milwaukie, and near the Falls of 

 Wolf River, near its extreme borders north and south, it is somewhat mingled with 

 beds of coarse gravel ; and also on the bluffs north of Tayhedah, on Lake Winne- 

 bago, near its superior face or greatest elevation. It makes a good wheat soil, 

 especially where, as is frequently the case, there is a shallow stratum of sandy 

 matter on its surface. Its age cannot as yet be determined, for want of fossils. At 

 Appleton, on the Fox Eiver, in a well, pieces or splinters of well-preserved wood 

 were found at the depth of thirty feet. 



It is remarkable that the heavy clay and marly deposits of Lake Erie, Lake 

 Michigan, and Lake Superior, are found in their principal force, on the west sides 

 and ends of those fresh-water seas, and that the presumption is, that the deposits 

 themselves are all from fresh water, and very recent. 



It is in the red clay of Wisconsin that the inhabitants of the towns on Fox River 

 sink their Artesian wells. 



Artesian Wells. — The village of Fond du Lac is situated on the red clay, not 

 much elevated above the level of Lake Winnebago. The clay being compact, and 

 impervious to water, did not give to ordinary wells anything like living water. 

 They served only as the receptacle of surface-water. The idea was conceived of 

 boring into the clay to greater depths than ordinary wells. Mr. A. Curtis under- 

 took the work for Mr. G. M' Williams, and the plan succeeded remarkably well. 

 There were (October, 1849) eighteen of these wells in the village, varying in depth 

 from seventy to one hundred and ten feet, Mr. Curtis informed me that the order 

 of stratification is everywhere the same, and reckoning in the descending order, as 

 follows : 



Feet. 



1. Red marly clay, . . . . . . . 30 to 40 



2. Blue clay, with strips of quicksand, . . . . 40 to 60 



3. Sand and gravel, . . . ... . 1 to 3 



4. Lime-rock (Silurian). 



* Some of the Fond du Lac clay (Specimen 99) is said by the workmen to contain too much lime to 

 stand the heat of the arches. Dr. Owen's analysis of the red clay of Bad River, Lake Superior (Speci- 

 men No. 46 of my collection), gave protoxide and peroxide of iron, 10-7 per cent., which, by burning 

 in the fire-place, makes a good fine-grained red brick; while the cream-coloured, hard-burnt brick (Speci- 

 men 98 of my collection), from Neenah, on the Fox River of Green Bay, gave a still greater percentage 

 of iron, and this red clay, when moderately burnt, is red, when hard-burnt is rream-rotonr. 



