QUATERNARY FORMATIONS — THE DRIFT. 223 



ity of Port "Washington it reaches its maximum observed thickness of 

 75 feet, although it doubtless somewhat exceeds this at some points. 

 At many places along the lake shore, owing to slides and washing, 

 it appears to have a thickness considerably exceeding this. 



It has a wide surface distribution, as will be seen by consulting the 

 accompanying map. Commencing near Milwaukee, it widens to the 

 north until the Kettle Eange is reached, by which its western boun- 

 dary is deflected to the eastward iintil it passes that barrier and swings 

 around upon the western side, and, passing the watershed, occupies 

 the Green Bay valley. It ascends this valley to a few miles south 

 of Fond du Lac, and reaches up the Upper Fox river beyond Berlin, 

 while in the Wolf river valley it extends beyond Shawano. "West of 

 the bay it appears in much less amplitude than to the southward. 



From what has already been said concerning this and the underly- 

 ing formations, no doubt remains that it was a subaqueous deposit. 

 Its extent should, therefore, indicate approximately the amount of the 

 encroachment of the lake at the time of its formation, and the alti- 

 tudes to which it rises are signiiGlcant of the amount of relative de- 

 pression that attended its formation, and hence, an especial interest at- 

 taches to its vertical distribution. At its southern extremity, it reach- 

 es an altitude of a little more than 100 feet above Lake Michigan. 

 "Where its western limit crosses the north line of Ozaukee county it is 

 about 200 feet. A few miles east of this it rises upwards of 300 feet. 

 At the northwest corner of section 36, town of Lynden, Sheboygan 

 county, it is 315 feet. In the town of Rhine, of the same county, the 

 limit is found at 322 feet; at the middle of the north line of section 

 21, town of Memee, Manitowoc county, at 248 feet, and on the oppo- 

 site side of the Kettle Range, at St. Nazian, at the same height. 

 North of this its limitation is less well defined. There are some in- 

 dications that it passed entirely over the Kettle Range, in the central 

 portion of Manitowoc county, or at least that the waters of the period 

 did. Nowhere north of this was it observed at a height exceeding 330 

 feet above Lake Michigan. Near Chilton it reaches an elevation of 

 372 feet; north of Stockbridge, 358 feet; south, 390; in station 6, 

 Marshfield, 401 feet; in section 5, Taycheedah (T. 15, R. 23), 315 feet. 

 These have been selected from a large number of observations, either 

 because more reliable, or because more significant, on account of their 

 positions. A more general and comprehensive appreciation of the 

 facts may be gained by a comparison of the map of Quaternary For- 

 mations with the Topographical map, both of which will be found 

 upon plate lY, conveniently arranged for such comparison. It will 

 be observed that the formation rises gradually from its southern ex- 



