INDEX. 
Woolwich and Reading Beds, 844 
Worms, burrows and irails of in strata, 
485, 911; castings of in relation to the 
formation of vegetable soil, 339 
Wyoming, “Bad Lands” of, 343; Cre- 
taceous rocks, 831; Eocene, lakes of, 
394; volcanic action in, 209 
Xanthopsis, 846 
Xiphodon, 856 
Xylobius, 732 
Yang-ise. sediment in water of, 371 
Yazoo River, relation of discharge to rain- 
fall, 361 
Yellow as a colour of rocks, 92; colours of 
soil due to oxidation and hydration by 
rain, 339 
Yellowstone River, caiions of, 205; geysirs 
971 
of, 223, 236, 354; mud-voleanoes of, 
234; daily range of temperature at, 
319; terraces of, 384 
Yew, early forms of, 838 - 
Yoldia (Leda), 895* 
Yoredale Group, 737, 738 
Yorktown Group (Tertiary), 869 
Zamia, 772* 
Zamiostrobus, 772 
Zamites, 761, 772 
Zanclean (Pliocene), 878 
Zaphrentis, 664, 721* 
Zechstein, 756 
Zeolites, 72, 80 
Zeolites, formation of in Roman brick, 300, 
353 
Zircon, 80 
Zones in geological record, 635 
Zygosaurus, To4 
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