Wales once lived the ancient British tribe of 

 Silures or Siluna. hence tbe name to designate a 

 remarkable etratification of rock, showing well to 

 the front in this didtrict and often referred to 

 as the Ladlow. Wt nlock and Llandeilo groups. 

 The Silurian beds are world wide ; all tell of coral 

 reefs, sandy shores, fish and marine life, shell beds, 

 gravel beaches, and deep seas. As an industrial 

 strata, it is not of so much value as the Cam- 

 brian, but the Silurian sj'stem, or sets of strata, is 

 the chief source of gold. 



Devonian. — There is a book found in many 

 libraries called " Old Bed Sandstone," a most 

 useful little work dealing with the next great 

 division of rocks known as Devonian, because, 

 although they are widely diffused, and rsach the 

 Arctic circle, th^y are particularly to the front in 

 Devon, hence the name this system bears. In 

 these rocks we find many remains of vegetation, 

 and the earliest known real trees, showing the 

 concentric rings of growth in their trunks ; insects 

 have here lett tbeir traces, but no land animals 

 and no reptiles, and the silence of the new earth 

 had not as yet been broken by the song of birds. 

 The waters, however, swarmed with fish, and 

 from tbe splendour of their coloured scales these 

 fish are knuwn as " Ganoids." These fish are tbe 

 first or earliest known vertebrates. Sponges, sea 

 lilies, and shell fish were abundant. 



Carhoniftro"S. — Following the Devonian, wo 

 have the C^irboniferous system, which, containing 

 oar principal deposits of coal, is of immense com- 

 mercial value, la addition to the coal, it is here 

 that we find ironstones, sandstones, grits, fireclays, 

 and limestones. la the back ages, when the 

 climate was both hot and moist, vegetation thrived 

 in tbe swamps and plains in a most luxurious 

 and prodigal manner, and in hundreds of known 

 oases, these forests were submerged again and 

 again. Floods and rivers overwhelmed the plant 

 life with sand and mud ; in the course of centuries, 

 vegetation again covered the land, only to share 

 the fate of the forest underneath, and by the 

 accumulation of the ages, vegetable matter was so 

 chemically altered and compressed, that coal was 

 formed in corresponding seams. First merely a 

 peat bed, composed chiefiy of club mosses and 

 tree furos of gigantic size ; with increase of 

 pressure, peat turns into lignite^ or brown coal ; 

 with more pressure it becomes house coal (as 

 found at Dover), which is soft and soils the fingers. 

 Anthracite is a harder, smokeless coal; Cannel 

 coal and "jet" was vegetable matter covered by 

 water so that its gases could not escape, and, al- 

 though so hard that it can be carved into orna- 

 ment?, and does not soil the fingers, it is so full of 

 gas, that it will kindle at a candle, hence "candle" 

 or "cannel" coal. As many as fifty seams of coal 

 are knowa to alternate one above the other, and 

 in tbe coarse of millions of years, this wonderful 

 plant life was abstracting the carbon from the 

 atmosphere and transforming it into organic sub- 

 stances fur tbe service of men when the set time 

 flbould come. This carboniferous system or strata 

 yields more of value and variety than all tbe other 

 systems put together. It was an age of abundant 

 and gigantic 6"ra, an enormous profusion of rapid 

 growth for a long continued epoch, unparalleled in 



luxuriance in tropical heat and moisture. In the 

 Lancashire district tbe system is about four miles 

 thick. Asphalt and petroleum are the products 

 of the decomposition of earlier vegetation. Under 

 every seam of coal is the mud, in which the coal 

 plants struck their roots ; it is now known as fire 

 clay, and is of tbe greatest value in the construc- 

 tion of furnaces. Not only do we from these strata 

 get our c^al and oil, our fire clay and building 

 stones, but also lovely dyes, exquisite perfumes, 

 drugs, and saccharine 300 times sweeter than cane 

 sugar. It is in these rocks that the first evidences 

 of spiders, scorpions, snailg, and beetles are seen. 

 Remains of tbe cockroach are found, historically 

 one of the most ancient, and structurally one of 

 the most primitive, of our surviving insects. No 

 vertebrate among land animals is seen before the 

 deposition of this carboniferous system, and here 

 we find the first, and simply through the labyrin- 

 thine structure of its teeth, it gets the name of 

 "Labyrinthodont"; it was a small aniraal of the 

 long extinct salamander type, and was amphibious. 

 Very few trilobites are found in this system, and 

 they appear no more. Forerunners of the beauti- 

 ful ammonites are here found, and the first known 

 oyster appears and has managed to survive, for 

 which, not a few are more than grateful. 



Permian. — Over the coals and the carboniferous 

 system we find a series of rocks, of which the chief 

 are red sandstones, marls, and magnesian lime- 

 stones, and, being so very pronounced in tbe Pro- 

 vince of Perm, in Russia, these beds are known as 

 the " Permian " system. At this period the life on 

 land and in water was much about the same as in 

 the preceding carboniferous s^ stem, bat it is in the 

 Permian tkat the first remains of true reptiles are 

 found, and these chiefly of tbe crocodile type. 

 This was also a period of great volcanic activity, 

 during which great masses of granite were thrust 

 up, forming Lands End and Dartmoor, and active 

 volcanoes ejected their steam and lava in several 

 parts of England and Scotland. The limestones 

 ountaining magnesia were probably deposited in 

 salt lakes like the Dead Sea, so forming magnesium 

 or dolomite. Sulphate of lime would be deposited 

 through the same cause and from gypsum. 



Triassic. — With the Permian strata we leave 

 what are known as the primary or Palaeozoic rocks, 

 far below the surface of the ground, and enter on 

 tbe rock foundations of the secondary or Mesozoic 

 epoch, and the widely different features of the 

 plant and animal life of tbe next system, known 

 as the Triassic, tells of an enormous lapse of time 

 from the modification of tbe life forms. The 

 system takes its name from the threefold division 

 of these rocks as found in Germany, known as 

 Rbsetic, Keuper, and Banter ; mostly red sand- 

 stones, shales, limestones, marls, and pebble beds. 

 These rocks in England produce rook salt and 

 gypsum, and in them is our brine supply, as at 

 Droitwicb,etc. At Burton-on-Trent, the waters of 

 these Triassic rocks carry sulphate of lime, or 

 gypsum in solution, which makes it of each value 

 in this great brewing centre. The Derbyshire 

 alabaster is in great demand for many works of 

 art. Most of the older forms of life have disap- 

 peared, and it IS in this system that the first re- 

 mains of mammals come to light ; teeth have been 



