CONTENTS. 
Page. 
Introduction 7 
Climate and vegetation 8 
Topography . - 12 
Mountains 13 
Valleys 18 
Hydrography 21 
Drainage slopes 21 
Streams 21 
Springs and artesian wells 23 
Artesian basins 25 
Lakes .. 27 
Cow Creek lakes .. 27 
Malheur and Harney lakes 29 
Silver Lake 32 
Lakes of Alvord Valley 33 
Fluctuations of lakes, efflorescences, etc 34 
Geology 36 
Recent volcanoes 36 
Cinder buttes 38 
Breached cinder cones and floated crags of tuff . 39 
Volcanic bombs 40 
Lapilli cones, cinder cones, etc 45 
Jordan craters 48 
Crater No. 4 : 49 
Driblet cones and ; ' ovens " 52 
Lava gutters 52 
Lava flow , 53 
Diamond craters 54 
Bowden crater 57 
Summary 58 
Tertiary formations _ . 59 
Sedimentary rocks - 60 
Igneous rocks 64 
Volcanic rocks 64 
Dike rocks 66 
Structure 67 
Mineral resources 69 
Petroleum 69 
Conditions favoring natural storage of petroleum and rock gas 69 
Index _ - 81 
3 
