The Natural History of Clay

by Alfred B. Searle

CHAP.		PAGE
	Table of clay rocks	[viii]
I	Introduction. The chemical and physical properties of clays	[1]
II	Clay and associated rocks	[48]
III	The origins of clays	[70]
IV	The modes of accumulation of clays	[84]
V	Some clays of commercial importance	[103]
VI	Clay-substance: theoretical and actual	[135]
	Bibliography	[168]
	Index	[170]

LIST OF ILLUSTRATIONS

FIG.
1	Quartz crystals	[9]
2	Pyrite	[14]
3	Marcasite	[14]
4	Illustrating the structure of a 'clay crumb'	[24]
5	Chart showing rates of drying	[27]
6	Seger Cones indicating a temperature of 1250° C.	[34]
7	Ludwig's Chart	[36]
8	Coal Measures sequence in North Staffordshire	[55]
9	Lias clay being worked for the manufacture of hand-made sand-faced roofing tiles	[58]
10	Oxford clay near Peterborough	[60]
11	Cliffs of Boulder clay at Filey lying on Calcareous Crag	[66]
12	China clay pit belonging to the North Cornwall China Clay Co.	[72]
13	Orthoclase Felspar	[75]
14	Illustrating the successive deposition of different strata	[90]
15	Lacustrine clay at Skipsea	[92]
16	Clay at Nostel, showing Marine Band	[94]
17	Kaolinite and Mica	[105]
18	Mining best Potter's clay in Devonshire	[111]

THE CHIEF CLAY ROCKS (arranged geologically)

Tertiary		Recent (alluvial clay, silt, brick earths, boulder clay)
		Pliocene Miocene Oligocene Eocene		(brick earths, ball clays, coarse pottery clays)
Secondary		Cretaceous (cement clays, brick clays)
		Oolitic (brick and tile clays)
		Triassic (brick, tile and terra-cotta clays)
Primary		Permian (brick, tile and flower-pot clays)
		Carboniferous (brick clays, fireclays, ganister)
		Devonian Silurian Ordovician Cambrian Pre-Cambrian		(clay schists, slates and clay shales)
		Igneous Rocks occur on several horizons (china clays and kaolins)

(In the above Table only the clay-bearing strata are mentioned. The formations named consist chiefly of other rocks in which the clays form strata of variable thickness.)

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CHAPTER I