264 Wieland — Eopaleozoic Hot Springs, etc. 



above. The most distinct of these bowlders are found within 

 an area of less than one square mile, and this is exactly the 

 area of the best marked oolite. It should be stated that 

 neither oolite nor bowlders have ever been observed except as 

 surface debris. This may be due to the fact that the oolite 

 probably never formed a very continuous stratum, as well as 

 to the fact that there is neither rock exposure nor excavation 

 within the oolite area. Both bowlders and oolite no doubt 

 belong to the underlying rock, which I suppose from its position 

 and the character of exposures of the same horizon at another 

 point to be Calciferous. There occur associated with the oolite 

 at one or two points, certain bowlders showing only traces of 

 oolite which contain nearly obliterated traces of numerous 

 fossils. I would say that brachiopods, cyathophylloid corals, a 

 gasteropod, and numerous orthoceratites are represented. 



The- cuts of the bowlders illustrate their form and cleavage 

 fairly, but do not show the pitting of the surface due to weath- 

 ering. The bowlders are much iron-stained and somewhat 

 granular in texture, though breaking most readily along the 

 cleavage planes which radiate from the inner edge of the circular 

 rims of which they may be regarded as segments. The direc- 

 tion and position of these planes are best shown in figs. 2, 4, and 5. 

 What was probably the upper surface is roughly but regularly 

 grooved, as best shown in fig. 1. These groovings mark more 

 or less nearly the emergence of the cleavage planes just men- 

 tioned. The bowlder shown in fig. 6 lacks the built-up struc- 

 ture, and may have formed within an already formed rim. 

 There are occasional small rhombohedral cavities as in the 

 oolite itself, — a pseudomorphism after calcite. 



Under the microscope the material is found to be chalce- 

 dony, with small crystal inclusions which were too minute to 

 determine. I suspect these crystals to be biaxial, and they may 

 be from their shape hornblende. 



The rims which these bowlders formed had an inside diam- 

 eter of from two to six feet. The inner edge is always pre- 

 served, while the outer is often irregular or broken away. We 

 may readily conceive the bowlders as having formed the rims 

 of a number of hot springs or geysers near a low-lying shore of 

 the Calciferous. The dissolved silica first deposited would have 

 formed rings, that deposited while in more rapid motion the 

 small spheruled oolite, which is most plentiful near the best 

 marked of the rim bowlders. Lastly would be formed large 

 grained oolite, the compact and pure quartzite, which is the 

 handsomest oolite known. That in accounting for the origin 

 of this oolite hot springs or geysers of the Calciferous may 

 actually be located is an interesting consideration. While the 

 writer has not had an opportunity to examine a geyser region, 

 he believes that further investigation will sustain his view. 



Chester^ Pa. 



