KANSAS ACADEMY OF SCIENCE. 19 



of St. Louis, for the numerous fractures in those rocks, is entirely inadequate. 

 To avoid an unnecessary repetition, it has been thought best simply to exhibit 

 characteristic specimens at present, and give to those interested the above 

 reference for a fuller discussion of the subject. 



Specimen No. 1 is a fragment of chert with fossil corals on one side. It 

 has evidently been adjoining a limestone, as a number of the prominences 

 on the fossiliferous side are limestone. 



No. 2 is a specimen of what is locally called "cotton" rock. It exists 

 very abundantly along the northwest limit of the Sub-carboniferous, partic- 

 ularly in Jasper county, Mo. It shows a mass of fragmental crinoid stems, 

 one of which is fully six inches long; also a few other fossils common in this 

 formation, among which is a trilobite. 



No. 3 is a cherly rock with crinoids and other fossils. 



No. 4 is a sample of what has been called volcanic tufa. 



No. 5 is a specimen of the same, but in this small specimen, which weighs 

 less than half a pound, there are more than fifty fossils. 



No. 6 is a similar specimen. 



No. 7 is a sample of decomposing chert, the center of whioh is still 

 unchanged. 



Nos. 8 and 9 are samples of rocks containing cavities from which crystals 

 of sphalerite (zinc blende) have been removed. 



Nos. 10, 11 and 12 are similar specimens, which still retain a portion of 

 their crystals, although they have been strongly acted upon apparently by a 

 solvent. These show conclusively that the crystals were formed prior to the 

 formation of the rock around them ; otherwise the crystals would have assumed 

 the shape of the cavities in the rocks, which would not have corresponded 

 exactly to the crystalline form of sphalerite. 



No. 13 is a collection of sphalerite crystals, which also show the eflTect of 

 some solvent. This specimen has not been above ground more than ten 

 days. 



Nos. 14 and 15 are specimens of galena crystals, partly removed by a 

 solvent. The same may be said, with reference to the time of their for- 

 mation, that was said when speaking of the sphalerite crystals. If we will 

 now consider the great range of temperature between the fusing points of 

 those two minerals and that of the surrounding rock, and also consider the 

 invariable result of fusing lead and zinc ores with silica — that is, the forma- 

 tion of silicates — wewill see at once that these, as well as the fossils, are pos- 

 itive evidence against the igneous origin of these rocks. 



No. 16 is a fossiliferous chert rock, upon which calamine (zinc silicate) has 

 been deposited, showing that the presence of this mineral is no evidence in 

 favor of the igneous theory. 



No. 17 is similar, only it shows that while the silicate was being deposited, 

 the chert was being dissolved. This act is carried so far that the form of the 

 chert rock is almost destroyed, but two fragmental fossils are still preserved. 



