Dixon, H. H., and AGnadance of Life, 60.
Double canals, formation by attraction of a satellite, 585-187.
Douglass, A. E., observations on Mars, 167.
Dravidian Era of India, 135.
E.
Earth, early history of, 3, 4; dimensions of, relative to surface
features, 117.
Earth's age determined by thickness of sediments, 5; determined
by mass of the sediments, 7; determined by sodium in the ocean,
12; determined by radioactive transformations, 19; significance
of, 2.
Earthquakes associated with geosynclincs, 142.
Efficiency, tendency to maximum, in organisms, 113, 114.
Elements, probable wide diffusion of rare, 230; rarity of
radioactive, 241.