692 



SCIENCE. 



LN. S. Vol. IU. No. 71. 



a number of counties ranging, inclusively, 

 from St. Charles, Warren, Montgomery and 

 CaUaway counties (which lie west of St. 

 Louis), on the north; through Jefferson, 

 Franklin, Gasconade, Osage and Maries, 

 to Crawford, Phelps and possibly other 

 counties on the south, the whole area oc- 

 cupjdng about the center of the eastern 

 half of the State, its northern boundary 

 being but a few miles north of the Missouri 

 river. 



These clays are of uncertain geological 

 age. The beds of clay as they now occur 

 are probably the last remnants of a once 

 very extensive formation in this region. 

 They are to be found mostly in the minor 

 lateral valleys along the borders of the 

 greater ones, and apparently always near 

 the tops of the valley sides. They some- 

 times occur in shallow pockets along the 

 tops of the divides, this being especially 

 noticeable in Gasconade county, where these 

 clays occur over a wide area. The greatest 

 thickness of this clay seen by the writer, 

 was at Eegina, Jefferson county, where a 

 pocket had been opened to a depth of sixty 

 feet. Borings have been made in pockets 

 which seem to belong to this class, which 

 penetrated the clay to a depth of one hun- 

 dred and twenty-five feet. In all of the 

 many pits of this sort observed the con- 

 tact between the clay and the surrounding 

 sandstones or limestones was sharply uncon- 

 formable, and indicated the origin above 

 suggested. 



The clay is usuallj^ cream-color, but is 

 often mottled with purple and reddish tints, 

 which are organic stains and readily dis- 

 appear on ignition. It is mostly hard and 

 brittle, breaks with a conchoidal ii-acture, 

 and weathers concentrically, breaking up 

 indefinitely into sharp, angular fragments. 

 It is mined (as a fire-clay) mostly in Mont- 

 gomery, Warren, Franklin, Crawford, Gas- 

 conade and Phelps counties, for shipment 

 only, going to fire-brick works in St. Louis, 



Chicago and Eastern cities, where it is used 

 in connection with more plastic clays to di- 

 minish their shrinkage. 



In one locality near Union, in Franklin 

 county, the upper four or five feet of this 

 clay is plastic. Another variety occurring 

 in many places is white, brilliantly mot- 

 tled with reddish tints, and sometimes 

 stained very dark purple : is comparatively 

 soft and free from sand ; has a smooth, 

 soapy feel and is cut with a knife in an ex- 

 tremely smooth, soft way. 



These three phases, the hard fire-clay, the 

 plastic clay, and the last-mentioned variety 

 — called locally ' kaolin ' — jnauy represent 

 different horizons in this group of clays, and 

 it is probable that the variety called ' kao- 

 lin ' is part of the same formation which is 

 found southeast of this region, where it has 

 been considered a true kaolin, occurring in 

 the place of its origin among the parent 

 crystalline rocks. 



The onlj^ trace of organic remains found 

 in this group by the writer was taken 

 ■ from the clay pit of Isidor Mandle, in Ee- 

 gina, Jefferson county (where the clay is 

 worked and shipped east to porcelain facr 

 tories). This specimen consisted of apiece 

 of beautifully carbonized wood, nearly two 

 feet in length, and five inches by three 

 inches, in cross section, at its larger end, 

 whence it tapered towards the other end to 

 about half that size. A piece of this wood 

 was sent to Prof. F. H. Knowlton at the 

 Smithsonian Institution, who prepared sec- 

 tions of it for microscopic examination and 

 kindly furnished the writer with the follow- 

 ing information in regard to it, which is 

 given in his own words: 



" The structure is very finely preserved 

 and comes out beautifully. It belongs to 

 the genus Dadoxylon, and is verj^ close to 

 Dadoxylon Beinertianum Endl., from the 

 Sub-carboniferous Falkenburg in Silesia. 

 The wood cells have one, or more often two, 

 alternating rows bordered with oblong cells 



