b CONTENTS. 
Geologic history — Continued. Page. 
Quaternary (?) events — Continued. 
Third canyon cutting (i(i 
Formation of flood plains 66 
Resume of history 67 
Correlations 68 
Explanatory statements 68 
Comparison with Lake Bonneville history 68 
Comparison with southern California 71 
Comparison with the Pacific coast » 71 
Comparison with the Plateau region 72 
Water supplies. 74 
Surface waters 74 
Precipitation 74 
Evaporation 74 
Streams 74 
Colorado River 74 
Flow 74 
Irrigable lands 74 
Dam sites 75 
Big Sandy Wash and Williams River _ 77 
Underground waters 77 
Surface indications 77 
Wells 78 
Nelson 78 
Peach Springs 78 
Hackberry 78 
Kingman 78 
Gold Basin 78 
Drake 78 
Yucca 79 
Haviland 79 
Big Sandy Valley 79 
Harrisburg 80 
Other wells 80 
Deep-well temperatures 80 
Notes on the igneous rocks of western Arizona, by Albert Johannsen 81 
Pre-Cambrian crystallines 81 
Effusive rocks 82 
Older andesite 82 
Rhyolite series 83 
Younger andesites 85 
Olivine basalts 88 
Dike rocks 90 
Olivine diabase 90 
Rhyolite porphyry 90 
Rock samples from northwestern Arizona 91 
Index 93 
