MICROSCOPIC STRUCTUHE OF SILICIOUS OOLITE. 629 



gates of fragments of quartz and making the cement bet\\een the spherules of the 

 same substance, while some of the quartz grains were caught in this chalcedony 

 cement without being made the nuclei of spherules. 



SiLicious Oolite feom Xew Jersey. 



The writer is inde1)ted to Professor C. E. Beecher, of Yale University, for a thin 

 section of this rock and tlie photograph from whicli figure 2 was made. This oolite 

 is from the Tertiary beds at an unknown locality in Xew Jersey. The granules are 

 small and very irregular in size, varying from 0.12 to 0.93 of a millimeter in diameter, 

 and vary from almost perfect spheres to much flattened ovoids and subangular 

 bodies. The concentric structure is very pronounced in most of the granules, and 

 many times the rings contain dark spots of indeterminate character, arranged 

 radially to the sphere. For the most part the spheres are without apparent nuclei 

 and are regular spluerocrystals of chalcedony. Occasionally, however, one is seen 

 with a more or less irregular nucleus of fine grained quartz. The matrix is partly 

 chalcedony and partly fine granular quartz, with isolated large grains of quartz 

 scattered through it. No deposit of fibrous chalcedony as incomplete shells outside 

 the granules was-observed in this section like that so common in the Pennsylvania 

 rock. Xo organic remains were noticed in the section studied. 



EXIM.AXATION OF PlaTE 21. 



Figure 1. — Silicious oolite from State College, Center county, Pennsylvania. Polar- 

 ized light. X 45. 



A. Rounded fragment of clear quartz. 



B. First zone of enlargement, cloudy quartz. 



C. Second zone of enlargement, clear quartz. 



D. Zone of granular quartz. 



E. Zone of short filjrous chalcedon}'. 



F. Outer shell of almost aphanitic chalcedony. 



(t. Incomplete shells of chalcedony with relatively long fibers. 

 The cross lined spots in the nucleus of the complete spherule seem to be of iron 

 oxide. The broad black line in the lower left hand corner is a crack which seems 

 to have been filled with iron oxide. 



Figure 2. — Silicious oolite from Xew Jersey. Ordinary light. X 24. 

 The last paper was read by title on account of the late hour : 



CHANNELS ON DRUM LI NS, CAUSED BY EROSION OF GLACIAL STREAMS 



JJY (iEORGE II. IJARTOX 



An abstract of this paper is published in The American Geologist, 

 volume xiii, March, 18U4, page 224. 



At the close of the meeting, Friday evening, 10.30, the following reso- 

 lution was offered hy Mr J. Stanley-Brown and unanimously adopted : 



Resolved, That the hearty thanks of the Geological Society are offered to the Boston 

 Society of Xatural History for its generous hospitality ; to the Local Committea, 



LX.KXVII— Bull. Geol. Soc. Am., Vol. 5, 189.3^. 



