Slate, clay, [466].

Slichter, C. S., cited, [195].

Slickensides, on fault, [60].

Smith, George Otis, cited, [173].

Smithsonite, [456].

“Smoke” of volcanoes, nature of, [128].

Smyth, C. H., Jr., cited, [157].

Snake river, Idaho, lava plains of, [102].

Snickers Gap, [177].

Snow, B. W., cited, [193].