10 EXPLANATION OF PLATE 1. 



Explanation of Letters and Figures used in the references to 

 unstratified and crystalline Rocks in Plate 1. 



a. Granite. b. Sienite. c. Porphyry, 



d. Greenstone. e. Serpentine. f. Basalt, or Trap. 

 g. Trachyte. h. Products of Extinct Volcanos. 



i. Products of Active Volcanos. 



a. 1. — a. 3. Mountains of Granite, raised into lofty ridges, 



from beneath Gneiss and Primary Slates, 

 a. 4. Granite intermixed with Gneiss. 

 a. 5. — a. 8. Granite, subjacent to stratified rocks of all 



ages, and intersected by volcanic rocks. 

 a. 9. Granite Veins, intersecting Granite, Gneiss, and 



primary Slate, 

 a. 10. Granite Vein, intersecting Primary and Transition 



rocks, and forming overlying masses at the surface. 



a. 11. Granite Vein, intersecting Secondary strata, and 



overlying Chalk. ''^ 



b. Dykes of Sienite. 



b. 1. Overlying masses of Sienite. 



c. Dykes of Porphyry. 



c. 1. Overlying masses of Porphyry. 



d. Dykes of ancient Greenstone. 



d. 1. Overlying masses of the same. The Rocks repre- 



sented by d. and e. often pass into one another. 



e. Dykes of Serpentine. 



e. 1 . Overlying masses of Serpentine. 



f. Dykes and intruded subterraneous masses of Basalt. 

 f. 1. to f. 7. Masses of Basalt protruded through, and 



overlying strata of various ages. 



* In the locality quoted in the Explanation of Plates, Vol. II. p. 

 6, the Granite wliich comes to the surface over the Chalk, is not 

 covered by Tertiary deposits, as represented in our section, PI. 1. 



