170 ANNALS NEW YORK ACADEMY OF SCIENCES 



attested to bv the \om^ exposures wliieli show individual strata extending 

 for many hundreds of feet without interruption. 



Such a hypothesis as the above would place the beginnings of the 

 Flemington-Hopewell fault series at a time immediately following the 

 intrusion of the Palisade-Eocky Hill diabase sill. Since this fault series 

 affects practically the highest horizons of the known Triassic in the New 

 Jersey-Pennsylvania section, this would place the intrusion of the Pali- 

 sade sill at a time about the close of the Triassic period of deposition here 

 represented, or perhaps a bit later. 



The joint series wdiich is at right angles to the principal series was of 

 earlier production, and must have been tightly closed and discontinuous, 

 since it contains none of the mineral deposits above descril^ed. 



With the ilmenite and analcite in the major joints and brecciated zones 

 at Princeton, crystallized barite appears. A quantity of barite is present 

 at Glenmoore, near Hopewell, N. J., and another similar deposit exists at 

 the western end of Buckingham Mountain, in Bucks Co., Pa., where the 

 Flemington and Hopewell faults unite. In both of these localities the 

 barite occupies a breccia, being evidently typical of this series of fauli 

 zones. Barite has been found in cavities of the Palisade diabase, at Ber- 

 gen Hill, N. J., in crystals two or three inches long and an inch thick. 

 Without doubt most of the local barite originated with the trap rocks, as 

 did the barite found with the ilmenite and analcite at Princeton. The 

 analysis, however, of E. B. Gage^^ shows that at least some of the Locka- 

 tong sedimentaries carry as much as 0.11 per cent of BaO. The circula- 

 tion of waters through such a rock might account for small occurrences 

 of barite. 



Titanium minerals, such as the ilmenite and brookite which appear in 

 such good development, require heat for their artificial production. Little 

 is known, however, of their exact mode of formation in nature. Analcite 

 is commonly associated with the minerals of the trap rocks, although 

 under very special circumstances it may be produced in other w^ays; it 

 does not require excessive heat for its production. The finding of anal- 

 cite as a close associate of minerals derived directly from the trap while 

 cooling, has a possibly important bearing on the origin of analcite in 

 some other localities where it is associated with the trap rocks. The dis- 

 covery of analcite wdth "Eisenrosen" of ilmenite and well formed brookite 

 crystals, on joint planes of sedimentary rocks, having at first sight no 

 connection with igneous action, is a matter of much interest. 



The Rocky Hill-Palisade diabase sill, although now much reduced by 

 erosion, must once have overlain much of the vicinity of Princeton. The 



23 Ann. Kept. State Geol. N. J., 1908. p. 06. 



