340 a. K. Gilbert on certain Glacial phenomena 



tribiited, glaciated boulders of all sizes up to a diam 

 twenty i'oet. It lias already been recognized bv Dr. Xrv . 

 as the sediment of a sea or 'ocean flanked by ghu-iors ami t. ■-• 

 ing rock-laden icebergs; and every phase that has fallen wwm 

 my own observation has served to connnn the identilir;i;ion. 

 Its more elevated portions, which have been ewnipt i'lMin 

 lacustrine action, present a rolling surface with frequen:. uii- 

 draiuvMl hollows, occupied by lakelets or the deep swam|i.- il.at 

 have resulted from tiicir slo^v tilling; while at and below the 

 le^ el of 220 feet (above Lake Erie) ihis surface has hrni iv 

 modelled and levelled by the waves, currents and sedinui. ■ ■ ;' 

 Lak'c Erie. 



Premising thus much of the gencjral character i>t' tlir 

 I will now ask the reader to notice, upon the a'-i'iiMij' 

 map, some peculiarities of the arranu-ement of the waUM'' 

 North of the Maumee river, where the land sloi)cMo thy - 



principal streams, the St. Joseph and TifHn rivers, cro- rre 

 system at right angles. Moreover, all the tributaries oi tliy >- 

 Joseph come from the northwest, while the country ea.-t oi'i: i> 

 drained by branches of the Tiffin, the divide between the w;>ier< 

 of the two streams running within five miles of the forn'or. 

 This feature is caused by a narrow step in the connirv— .i 

 natural embankment, that carries the St. Joseph across the lare 

 of the slope, as a mill-race is carried along the baidv of a stiram: 

 and that river may be said to result from theconflucnfeol east- 

 ward-flowing creeks that have found a barriei' in the rul.ne 

 which forms its eastern bank The slopes of this ridtic -n' 

 quite gentle and the height is moderate ; west of 15ryau. 'wli'-'re 

 it is crossed by a branch of the Lake Shore iiud MirlijLan 

 Southern Eailwaj^, it rises to an altitude of fifty feci. ^'''|"|^',f^^ 

 the north line of Ohio it is barely distinguishable. Suj'erfici:!!'.^ 

 it everywhere presents the same rolling gravelly clay a.-: tue 

 surrounding country. 



South of Fort Wayne the same phenomena are {)rc-^ontc'a :;5 

 the St. Marys river. The slope of the count iw i> t<>war.l ine 

 northeast, yet its course is to the northwest. Its trih'itano- art 

 from the south and west, while its right bank is drain-l ii} 

 branches of the Auglaize. Where the dividing ridge ha. d-ab 

 measured, it has an altitude of 35 to 50 feet ^ ^^ 



A con-elated feature of the two streams— the St. Mary.- J ^^ 

 St. Joseph— is that, forming the sides of a right auglo. tii^ 

 unite at its apex, and the resultant river returns Avithm ' 



^^^^^- ■ ^yu<^ 



The page of history recorded in these phenomena i? ^IJ^^^^ 

 means ambiguous, the ridges, or, more propeidy, the i'|^^ 

 which determines the courses of the St. Joseph and bt m-i ; 



