7o8 PETROLOGICAL ABSTRACTS AND REVIEWS 



Spangenberg, K. "Einige Anwendungen und Erweiterungen der 

 Einbettungsmethode," Centralhl. f. Min., etc., 1920, 352-62, 

 406-14. 

 Gives various applications of the immersion method. 



Steidtmann, Edward. "Origin of Dolomite as Disclosed by 

 Stains and Other Methods," Bull. Geol. Soc. Amer., XXVIII 

 (1917), 431-50. pis. 7- 

 Most dolomites were deposited in the sea. A minority were formed by the 

 replacement of limestones by undergrovmd waters. Pure dolomites and lime- 

 stones are far more abundant than mixed beds of limestone and dolomite. 

 The occurrence of calcitic casts in dolomite, or of hollow casts bounded by 

 perfect molds, indicate that the casts were deposited in dolomite. Dolomite 

 rhombs, imbedded in a hornlike impervious mass of fine-grained marine calcite, 

 were evidently formed in the ooze contemporaneously with the calcite. 



Tarr, W. a. '' Oolites in Shale and Their Origin," 5w//. Geo/, ^'oc. 

 Amer., XXIX (1918), 587-600, pis. 2, figs. 2. 



Describes certain oolites found in shale in the Wind River Mountains, near 

 Lander, Wyoming. They are believed to be due to direct precipitation of 

 colloidal silica by the electrolytic and saline character of the shallow waters 

 into which they were introduced by streams from the adjacent land. 



Tarr, W. A. "Origin of the Chert in the Burlington Limestone," 

 Amer. Jour. Sci., XLIV (191 7), 409-52, figs. 13. 



Believes the widespread chert which occurs in the Burlington formation 

 of Mississippian age has been formed from colloidal silica derived from inflowing 

 streams and deposited by electrolytic action. The ellipsoidal form of the chert 

 is attributed to the flattening of the colloidal mass under its own weight and 

 later by the weight of overlying sediments. 



Tilley, C. E. "The Petrology of the Granitic Mass of Cape 



Willoughby, Kangaroo Island, Part I, Trans. Roy. Soc. South 



Australia, XLIII (19 19), 316-41, pis. 2, sketch maps 2. 



The granitic rocks of Cape Willoughbv, Victor Harbor, and Port Elliot are 



thought to be chonolites connected below with a single batholith. They were 



intruded at the close of the orogenic movements in the region. The dominant 



rock is granite with minor intrusions of aplite and pegmatite. Interesting 



rocks are the albitites, quartz-albitites, and muscovite-albitites, which are 



regarded as the final differentiates from the residual magma. The first rock 



