Plate 8. — Thin Sections of Material from Meriden "Ash Bed." 



Figure 1.— Two greenish brown banded spherulites. The larger is radiate-fibrous 

 in each band and in the center. They are in a glass fragment, which 

 is devitrified precisely as the center of the large spherulites It con- 

 tains a thread of yellow glass. At the bottom, below the edge of the 

 glass fragment, is a calcite and calcedony deposit which cements the 

 fragments. Magnified 35 times. Meriden " ash bed." See page 74. 



Figurk 2. — Brown spherulite and glass drops in a colorless calcified glass breccia. 

 The drops are affected by a perlitic cracking, and the center has 

 contracted slightly from the curved films which have cracked off", 

 and these have broken and slipped by each other. The drops and 

 the center of the spherulite have suffered granular devitrification, 

 which extends to the glass outside the drops. In the outer layers 

 of both it is transversely fibrous. Magnified 35 times ; crossed nicols. 

 Meriden " ash bed." See page 74. 



Figure 3. — Shattered glass, with the fragments showing a fine fibrous devitrifica- 

 tion, which is in most places transverse to the surfaces of the frag- 

 ments, and is therefore subsequent to the shattering. The fibers are 

 like those of the spherulites, are radiate from many centers, and 

 show the black cross many times repeated. The fragments are ce- 

 mented by a plagioclase calcite mixture showing at the bottom of 

 the slide. The whitish part is calcite. Meriden " ash bed." Mag- 

 nified 35 times ; crossed nicols. See page 74. 



Figure 4. — Dark brown, wholly non-polarizing glass with many plagioclase rods 

 changed to granular calcite. A lighter band of yellow glass borders 

 the collapsed and half collapsed steam holes, in one of which a glass 

 thread is drawn out and bent upon itself. Directly below a cavity 

 is full of glass threads. From a great block of pure glass on the 

 bluff above the blasting at the Meriden "ash bed." Magnified 20 

 times. See page 73. 



Figure 5. — Another portion of the slide shown in figure 4. The deep brown glass 

 graduates into a light yellow brown, the latter dusted by ferrite 

 grains and showing the minute Assuring which causes the greasy 

 luster. A large, fresh diopside has been bent about 15 degrees with- 

 out fracture. This must have been done during the deformation of 

 the solid glass. Magnified 20 times. See page 73. 



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