48 



GEOLOGY OF IvA SAI^LE COUNTY. 



But the great mineral wealth of La Salle county 

 lies in her clays and coals. The clays are of several 

 kinds. First, g-lacial or drift clays lying- near the sur- 

 face, and containing- streaks or veins of sand, rounded 

 pebbles, and smoothed and scratched pieces of rock 

 from the size of a g'oose's eg-g- to those weig-hing- many 

 pounds. These vary considerabl;/ in composition, and 

 usually contain some silica, sand, lime and iron, a com- 

 bination which g-ives them a low melting point and un- 

 fits them for withstanding- a g-reat deg-ree of heat. 

 These make common brick. Second, clays overla}' ing- 

 the coal seams, g-enerally containing- much pyrite, but 

 less lime than the former. They are stratified, while 

 the first are seldom or but obscurely bedded. They 

 make fair brick, but are apt to pit in burning-. 



Third, underclays or clays lying- immediately be- 

 low the coal. These are the fire clays so valuable for 

 making- brick for furnaces and other v\ ork where a 

 hig-h temperature is employed. They diifer in quality 

 that beneath coal No. 2 being- one of, if not, the best. 

 It is larg-ely mined and quarried about Ottawa, has 

 been dug- on Co veil creek and at various points along* 

 the Big- Vermillion river. It is adapted to making- 

 fire-brick, drain tiles, sewer pipe, fire-proofing- for 

 lining- building-s, paving- brick and tiles, roofing- tiles 

 and many other thing's, and some of it makes very g-ood 

 pottery. There are in the Vermillion region clays 

 which can be worked into ware which burns of a 

 creamy white, and even when ung-lazed presents a 

 smooth surface. The location of this deposit is un- 

 known to us. Some years since, in the course of a 

 conversation, Mr. Murray Kirkpatrick informed us 

 that he knew at that time of forty-two varieties of 

 clay in the Vermillion valley, and it is safe to say that 

 for the county this number may be much increased, 

 certainly to not less than sixty varieties. 



