B. K. Emerson — The Deerfield J) ;/l a and it* Minerals. 349 



case with the 



as the overflows, outcrop along < 

 in the overflows results from a bending after their eruption ; 

 therefore the others also were probably bent after their intru- 

 sion. But it must be borne in mind that all of this is only 

 I'lvsuniptive evidence and not final proof; the age of the 

 intrusions is not yet determined. 



Art. XXXIX.— The Deerfield Dyke and it* Minerals ; by Ben. 

 K. Emerson, Professor of Geology in Amherst College. 

 [Concluded from page 278.] 

 Kaolin. — Along the shore in Greenfield opposite Turner's 

 Falls, and especially on the new road between these towns, the 

 decomposition of the radiated pi las ven iioquently 



taken a different course. The nodules are in whole or part 

 "hanged iutoji white kaolin (?). the change uniformly commenc- 

 ing from the different centers of radiation and proceeding 

 regularly outward. Under the microscope the kaolin-like 

 separates into opaque granules so extremely minute 



ful perfection. 



Calcitb. — Among the minerals associated with prehnite we 

 •'-'iiiv distinguish those which are enclosed by and themselves 

 enclose the latter, those which are only enclosed in it, and 



those which are superimposed upon it and are of later forma- 



In the first category calcite is the most common. The trap 

 at the base of the prehnite ell ■■r\ csces with acid, and some- 

 times cleavage surfaces of the latter resemble closely graphic 

 granite on a small scale, the prehnite takiim the place of 

 quartz, and if pieces where the calcite is specially abundant 

 be thrown in acid, there remains a delicate frost-work of preh- 

 nite on the trap, and similar groups of imperfect crystals are 

 exposed and fall to the bottom of the glass, being surrounded 

 011 ; dl sides by calcite. The calcite; which is thus intimately 



rs at tiroes in quite large masses 

 of transparent Iceland spar: more commonly in white granu- 

 ;; portions. Sometimes it is yellow and is perhaps ankerite. 

 "'be calcite is <iv after the prehnite 



::,h all the litter numbers of the 



series. It also occurs independently in the uppermost layer of 



the depth of a meter in the immediate vicinity of 



*be quartz veins mentioned later, though the two remain 



