CONTENTS. 



PAGE 



Board of Managers, xvii 



Letter of Transmittal, xix 



Preface, xxi 



PART l.-CLAY AND ITS PROPERTIES. 



Chapter I. Clay and its Mode oe Occurrence, 3-24 



Definition, 3 



Origin of clay, 4 



Residual clay, 6 



Sedimentary clay, 8 



Marine clays, 11 



Estuarine clays, 11 



Swamp and lake clays, 12 



Flood plain or terrace clays, 12 



Drift or bowlder clays, 13 



Secondary changes in clay deposits, 14 



Mechanical changes, 14 



Tilting, Folding, Faulting, 14 



Erosion, 17 



Chemical changes, 20 



Change of color, 21 



Leaching, 22 



Softening, 22 



Consolidation, 22 



Concretions, 23 



Shale formation, 24 



Chapter II. Methods of Working Clay Deposits, 25-38 



Prospecting for clays, 25 



Outcrops, 25 



Springs, 26 



Ponds, 26 



Vegetation, 27 



Exploitation of clay deposits, 27 



Adaptability of clay for working 29 



Methods of mining, 30 



Underground workings, 30 



Surface working, 32 



Haulage, 36 



Shale mining, 36 



Preparation of clay for market, 36 



Washing, 36 



Air separation, 38 



(iii) 



