viii

Figure 18.

23.

Camp Anthracite, plan of drift and crosscut.............
Camp Anthracite, section through coal seams............
Sketch of part of the wall of No. 3 Prospect opening at

Sate: Wilson a cis ccc cane Oe Se cena 6 soy sce ot
SeGhioncol Wiser Codl seals. (ssc: 6c pee wens ioe
(a) Sketch of northwest wall of crosscut in vertical Wilson

Generalized diagram illustrating the mode of occurrence of
tar in chalcedony-quartz amygdules and veins in basalt. .