20 KANSAS ACADEMY OF SCIENCE. 



Nos. 18 to 22 inclusive give some idea of the manner in which the chert 

 is fractured. 



Nos 23 and 24 illustrate that which is often seen on a grand scale 

 — alternating layers of chert and limestone. In specimen No. 3 there 

 is strong indication of limestone having been silicified. The specimen shows 

 three layers — an interior one, and two exterior ones. The interior one con- 

 tains by far the greater number of fossils, and may thus have been more 

 porous than the exterior ones. It would therefore have yielded more readily 

 to silicifying waters, and it is possible that the whole of the .specimen was at 

 one time a limestone. The exterior portion is at present quite calcareous, 

 even containing some carbonate. The theory advanced for the formation of 

 great beds of chert, requires conditions quite favorable for such metamor- 

 phisms. They are not only possible, but altogether probable. But can any- 

 one hold specimen No. 24 in his hand and say he thinks the chert in it was 

 at one time limestone? Let me repeat: It only represents on a small scale 

 that which exists on a large scale — alternating layers of chert and limestone. 

 Specimens 21 and 22 are good arrow-head flint, but 22 has many crinoid 

 stems in it. 



No. 2> is a concretionary formation containing fossils. If this was formed 

 in some cavity, how could those shells have been suspended in that cavity so 

 that they would have been included in the central portion of the concretion ? 

 If those shells were originally included in limestone, why would such a pe- 

 culiarly-shaped portion of that limestone have been silicified? If the lime- 

 .stone originally assumed this shape, why is it that similarly-shaped limestones 

 are not found in localities where they have not been silicified ? If they were 

 fragments of limestone, water- worn until they became of this shape, why are 

 the concentric layers so plainly marked? And why do some of them have 

 small cavities along their major-axis? And why do some of them have two 

 distinct centers around which the material has been collected, thus forming 

 a true twin concretion? 



FOSSIL WOOD. 



BY ROBERT HAY, JUNCTION CITY, KANSAS. 



Everybody in Kansas who has any collection of minerals or fossils, or 

 merely a handful of so-called curiosities, is sure to have a piece of fossil 

 wood. Inquiry develops the fact that the pieces were picked up on the high 

 prairie, in a dry ravine, in a creek bed, on a river bottom, or in almost any 

 conceivable situation. Some of these pieces are found in situ. They have 

 been petrified at or near the spot where they were found by agencies now or 

 very recently in operation. Elk creek, in Jackson county, yields petrifac- 

 tions in the form of iron pyrites; while a small tributary of McDowell's 



