MCHENRY AND LAKE COUNTIES. 127 



cent lucustrinc formation. This last character of the surface, however, is con- 

 fined to a narrow strip extending along the coast, from Waukegan northward , 

 and in its widest part, not more than two miles across. The ridges here are 

 composed almost entirely of sand, but nevertheless, support a growth of stunted 

 black and red oak, dwarf juniper, and occasionally, white pine ; their elevation 

 is but a very few feec above the lake. The outermost one is the widest, and 

 indeed, in many places, the only one, being constantly enlarged by accretions 

 along its lake front, and by the loose sand blowing inland from the beach, which 

 is itself a wide one, and is fronted by shallow water for some little distance 

 from the shore. The low prairie or marsh, between the ridges and the bluffs 

 is overflowed in many portions during a great part of the year, and in some 

 places is scarcely ever passable. In the firmer spots, there are occasional 

 clumps or thickets of bushes and low trees, but over the greater portion, the 

 only vegetation is rank grass and rushes. A strip of land of this general 

 character, extends along the coast nearly to the State line, gradually rising, 

 however, to the northward, and becoming dryer and more wooded. 



This low coast does not extend south of Waukegan, and the bluffs, which, 

 north of that place, are a mile or more inland, form the immediate coast to the 

 southward, in many places without even a strip of beach between their bases 

 and the water's edge. Being thus exposed, the bank crumbles rapidly under 

 the wearing influence of the waves of the lake, and in violent storms, large 

 masses are often undermined and carried away. Another frequent cause of 

 landslides is, the water percolating the clay from the top of the bank down- 

 wards, which, when the frost is coming out of the ground, or after long con- 

 tinued wet seasons, must affect materially the rapidity of the process of degra- 

 dation. The hight of the bluffs, however, some seventy or eighty feet, is such 

 as to render the inward progress of the lake upon the land comparatively slow. 

 The actual rate of wear could not be exactly ascertained, but from the appear- 

 ance of the clay bluffs themselves, I judged that in the course of years it might 

 be considerable, amounting, perhaps, to several hundred feet in a century. 



Inland from the bluffs, we find, for several miles, a gently undulating sur- 

 face, which, for the most part, was originally covered with a heavy growth of 

 timber, principally of the different species of oak and hickory, with a sprink- 

 ling of other kinds of trees. The soil is a light colored, somewhat arenaceous 

 clay or loam, with more or less admixture, in its upper portion, of organic mat- 

 ter, rendering certain portions slightly darker in color than the remainder. 

 The same general character of the soil prevails in the undulating timbered 

 tracts in all parts of the district, and also forms the subsoil of most of the 

 prairie. It appears to me to be a somewhat modified upper member of the" 

 Drift, and may be seen with the same general characteristics, in similar situa- 

 tions, in all of the northeastern counties of the State. 



