INTRODUCTION. XII 



stream of water, carries but a small amount of clayey or tine mate- 

 rial, and is less productive than the heavier soils on the borders of 

 this old stream course. In the immediate vicinity of Grand Rap- 

 ids it has the further disadvantage of being situated on the border 

 of a deep valley into which the water drains rapidly after a rain. 

 The lightness of the soil is shown in the character of the vegeta- 

 tion, it being a strip of "oak openings" whose flora is described 

 below. In this old stream course, the extensive Black Ash Swamp 

 has been developed; but, as in the lake outlet, this is due to subse- 

 quent plant growth, and sand may be found by probing to a depth 

 of a few feet. 



"The grade of soil next finer than the gravelly sand of the old 

 stream courses is the sand found on the bluffs of Grand and Thorn- 

 apple Rivers above the bend at Plainfield and on the border of 

 several small tributaries of Grand River, both above and below 

 Grand Rapids. These sandy deposits have apparently in some cas- 

 es been drifted by wind beyond the limits of the sti'eams that con- 

 tributed them, being very irregular and patchy. 



"The greater part of the Grand Rapids district lies on uplands 

 that were feebly or imperfectly acted upon by currents of water 

 during the melting of the ice sheet. As a consequence, the soils 

 contain a large amount of fine material together with the coarse 

 stones of the drift. The proportion of fine material determines 

 whether it is a heavy clay, a porous clay, or a loamy soil, and this 

 proportion often varies greatly within the limits of a small field. 

 In these uplands there are numerous basins formed by the irregu- 

 lar heaping of the drift, aided perhaps by unequal settling of the 

 drift material. These, because of imperfect drainage, usually con- 

 tain either lakes or swamps. The basins are especially numerouK 

 in Grand Rapids Township from Reed's Lake northwai'd, but are 

 not rare in any part of the uplands of this district." 



The indurated rock formations which underlie the drift have 

 furnished much of its material and are, therefore, of much import- 

 ance in a studv of the soil. 



