362 COUNTY AND REGIONAL GEOLOGY. 



grains of the bluff material. Tims, very serviceable bricks 

 are made, although they are lighter and more porous than 

 bricks made from ordinary brick clay are. It is necessary, 

 however, that this material should be entirely free from the 

 limy concretions which are often found in it, because if present 

 in the material when moulded, the burning of the bricks 

 converts the concretions into quicklime. The slaking of this 

 by moisture absorbed from the atmosphere, or from rains, 

 shatters and destroys the bricks. 



After what has been said in the preceding paragraphs, it 

 is almost unnecessary to a<Jd that no hope is entertained of 

 the discovery of a profitable bed of coal in Fremont county 

 except by deep mining. For a further explanation of the 

 veiws entertained upon this subject, the reader is referred to 

 the closing section of the chapter on the Upper coal-measure 

 formation. 



None of the soil of Fremont county may be properly called 

 drift soil, and only a very small fraction of it has any 

 admixture of drift in its composition. The latter occurs 

 only in the valleys where the drift has been reached by 

 their erosion through the Bluff Deposit. Even the alluvial 

 soils of the flood-plains are largely composed of material 

 derived from the Bluff Deposit. As to the quality of the soil 

 of this county, it may be confidently asserted that no country 

 in the world contains soil of greater fertility and that no 

 equal area contains a less proportion of untillable land. 



13. MONTGOMERY COUNTY. 



Boundaries and Area. Montgomery county is one of the 

 second tier from the southern boundary of the State, and is 

 of the same size and quadrangular shape as the majority of 

 them. It is three townships, or eighteen miles across from 

 its northern to its southern boundary, and twenty-four miles 

 in length from east to west. Consequently, it contains four 

 hundred and thirty- two square miles, or two hundred and 

 seventy-six thousand four hundred and eighty acres. 



Drainage and Surface Characters. Montgomery is 



