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PS eS ae i eres 
ILLUSTRATIONS 
PHOTOGRAPHS AND DIAGRAMS 
Percentage of earth’s surface at different levels 
Semi-opal, an amorphous mineral 
Group of crystals P 
Calcite, a crystalline mineral 
Group of quartz crystals 
Group of calcite crystals 
Black mica. 
Hornblende and asciis 
Hematite : 
Cubes of iron pyrite . 
Crystal and massive piece of Peat 
Railway spikes cemented together 
Consolidated gravel layer . 
Ropy surface of lava 
Lava with gas-made cavities 
Pumice 
Section of Staves culatiied nea Sinrsanne 
Section of gabbro enlarged by microscope 
An obsidian rock 
Granite 2 
Illustration of rate of ‘soéliug of; igaceae se 
Porphyritic rock 
Spherulites . 
Amygdaloidal rock 
Flow structure in lava : 
Stratification in a pebble of Gaia tonckstes and esrictatlonias 
Breccia 
Pebble beach, Sane dol — 
Conglomerate rock . : ? pare te Woke a 
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