western end of Lake Erie, and which formerly at successive 

 periods served to retain the waters of ancient Lake Erie or 

 Lake Whittlessey on the south, and which for a time emptied 

 its waters through the Ft. Wayne gap into the Wabash River. 

 The drift of the region is the regulation glacial till, such as 

 has been observed and studied throughout the glaciated por- 

 tions of the northern states. The soil content is largely made 

 up of sand and gravel with a small percentage of clay mater- 

 ial. The amount of clay or of the residues or any of the feld- 

 spars here, is extremely small when compared with that por- 

 tion of the till of the states further north. In Wisconsin for 

 example, and Illinois, the clay is often the chief constituent of 

 the soil, but wherever found near the lake under discussion, it 

 is of a light and soluble nature. 



The surface is in general undulating, with here and there 

 an abrupt knob and kettle area. These knobs are dom^ shaped 

 and the sides are frequently as steep as the material will lie. 



The basin or kettle is the exact opposite of the knob, 

 being formed into a deep rounded depression originally by the 

 melting of large masses of ice in the "till." These kettles are 

 trom various causes filled with water and many of them become 

 permanent lakes. Most of the lakes of northern Indiana owe 

 their origin to these depressions in the morainic ridges, 



There are several hill like elevations, probably eskers, 

 scattered about the region standing usually at right angles to 

 the strike of the drift. A particularly large one known as 

 Chicago Hill, stands near the Biological Station at Winona. 

 It is to all indications, a typical esker. It is composed of sand 

 and gravel heterogeneously mixed. Its shape is high and oval 

 but not lenticular and in these characteristics it is neither a 

 kame nor a drumlin. This esker as well as all of the elevations 

 of the region, has a vegetative covering varying in density 

 according to conditions. As a rule, the slope to the south and 

 southwest, owing to the exposure to the more direct heat in 

 summer and consequent drouth, bears a type of vegetation 

 approaching what is known among botanists as "Xerophytic." 

 On the northern side of those hills however, owing to the in- 

 creased shade and consequent addition of moisture, there is a 

 transition from the xerophytic vegetation to that type 

 known as "Mesophytic." As these and other ecological terms 



7 



