262 Wieland — Eopaleozoic Hot Springs and the 



Art. XXIX. —Eopaleozoic Hot Springs and the Origin of the 

 Pennsylvania Siliceous Oolite ; by Geo. E. Wieland. 



In seeking for more direct evidence as to the origin of the 

 siliceous oolites occurring near the Pennsylvania State College 

 in Center County, Pennsylvania, I have been led to the con- 

 sideration of certain associated flint bowlders of unusual regu- 

 larity of structure. 



Before describing these, however, it may be well to mention 

 that this siliceous oolite is the most perfect and beautiful of all 

 the oolites, and that its description* was the first given of a 

 characteristic siliceous oolite. Previously several occurrences 

 of cherts merging into oolite had been mentioned. Since then, 

 siliceous oolites of more or less distinct structure, and undoubt- 

 edly of various origin, have been reported from widely sepa- 

 rated localities, and geological horizons, though none are 

 known to be more recent than the Paleozoic. The cherts of 

 Missouri which often merge into a semi-oolitic structure have 

 been studied by Hovey.* 



Bat the oolites containing a large percentage of silica not 

 only vary much in structure, but much too greatly in compo- 

 sition to prevent any general statement as to their origin. 

 This is shown by the following analyses, made by the writer 

 while a student in the laboratory of the Pennsylvania State 

 College : 



I. II. in. 



Si0 o ._ 65-34 96-13 99*10 



Fe 3 1-13 -11 



A1 2 3 _.. .... -17 



CaO 10-35 -39 



MgO 7-91 -97 



K ._ _ .... '58 



C0 2 15-24 



H„0 1-85 -93 -25 



100*69 99-74 100'02 



JSTo. I is an oolite of granular texture, and in fact consists of 

 spherules of silica with a gangue of dolomite. This rock was 

 observed by the writer in a stratum of some twenty feet in 

 thickness near Pockwood, Tennessee. It was only casually 

 examined. A mile away on a lower horizon the iron oolite 

 of the Clinton was being mined. II is from the same 

 locality. Ill is the remarkably regular spheruled variety from 



* Barbour and Torrev: Notes on the Microscopic Structure of Oolites with 

 Analyses, this Journal. September, 1890. 



