CHAPTER IV. 



CAEEOLL COUNTY. 



Physical Geology. Carroll county is situated in the north-western 

 part of the State of Illinois, and is bounded north by Jo Daviess, east 

 by Stephenson, south by Ogle, Lee and Whiteside, and west by the 

 Mississippi river. It contains an area of about 450 square miles. By 

 surveys of the Illinois Central Railroad, its elevation above Lake Michi- 

 gan is about 400 feet, and above the mouth of the Ohio river at Cairo 

 about 800 feet. About one-third of the county, the north-western, is 

 somewhat rough, being mineral, or " lead-bearing n land. The surface 

 of this is hilly, and sparsely timbered, but in the valleys, along the 

 streams of this part of the county, many excellent farms have been 

 opened. The usual alluvial bottom skirts the Mississippi, being from 

 half a mile to four miles in width. Immediately adjoining the river 

 there is a belt of heavy timber ; but the rest of this bottom is composed 

 of drifted sand banks, marshy swamps, and rich tracts of the best pas- 

 ture and farming lauds. The southern and eastern parts of the county 

 are composed of gently rolling prairies, with here and there an island- 

 like grove, as if the fingers of the retiring ocean had stroked the soft 

 surface into swelling undulations. The agricultural portions of the 

 county are perfect garden spots rich in their almost virgin soil and 

 manifold resources of wealth. Xor is the county wanting in picturesque 

 scenery. Carroll creek, flowing west through its center, and Plum river, 

 running through its mineral land, have each cut channels deep into the 

 underlying rocks. These are piled about in massive grandeur are 

 crowned with evergreens ; and are, in many cases, the abodes of won- 

 derful echoes. Above Savanna, along the Mississippi river, the huge 

 towering Niagara rocks lift their heads like a Cyclopean wall. 



Geolot/ical position. We are deep down in the geologic world almost 

 in the line of union between the upper and lower Silurian systems. Three 

 distinctly marked groups of the rocks outcrop in Carroll county. These 

 are the Galena limestone, Cincinnati group and Niagara group. Above 

 these are the usual deposits belonging to the Quaternary system. 



