120 



LOWER CARBONIFEROUS VOLCANIC ROCKS OF EAST LOTHIAN. 



Hopetoun Monument) ; trachytes with porphyritic sanidine and plagioclase {e.g., 

 Phantassie Quarry, Skid Hill, and Bangley Quarry), and non-porphyritic trachytes (e.g., 

 Score Hill, Lock Pit Hill, Craigie Hill, and Pencraig). 



(3) The material filling the volcanic vents, comprising basic rocks (olivine-basalts 

 and limburgites), at Dunbar and Tantallon ; trachytes, at North Berwick Law and the 

 Bass Rock ; and a phonolite, at Traprain Law. 



EXPLANATION OF THE FIGURES. 



Plate I. 



Fig. 1. Limburgite of Whitelcav Hill, composed of olivine, augite, magnetite, and glassy matter. In 

 ordinary light. 



Fig. 2. Labradorite- Basalt of Jharkle Quarry, Garlton Hills, composed of porphyritic crystals of striped 

 labradorite and olivine in a microlitic ground-mass with granules of magnetite. Between crossed nicols. 



Fig. 3. Trachyte of the Bass Rock, composed of lath-shaped crystals of sanidine. Between crossed 

 nicols. 



Fig. 4. Trachyte of North Berwick Law, composed of lath-shaped crystals and microlites of sanidine. 

 Between crossed nicols. 



Plate II. 



Fig. 1. Phonolite of Traprain Law, composed of sanidine, nepheline, and green soda-augite. In ordinary 

 light. 



Fig. 2. Sanidine-Trachyte of Peppercraig, near Haddington, composed of sanidine and augite in a 

 microlitic (felspathic) ground-mass of glomero-porphyritic structure. Between crossed nicols. 



