CARBONIFEROUS ERA. 113 



simpler to more specialised forms. All the discoveries that 

 have been made, and are daily making, never controvert in 

 the least this great order of life ; nor do the ablest geolo- 

 gists, though anticipating many new forms, ever expect to 

 find it otherwise with creation than onward and still up- 

 ward. In this respect the coal-formation takes its place 

 orderly and in perfect harmony with what is known of other 

 formations : more prolific and more specialised in its forms 

 than the old red sandstone beneath, and less so than the 

 new red and other secondary strata that follow. 



Looking, in the mean time, at the whole aspects of the 

 carboniferous period, we are reminded (as we have else- 

 where* indicated) of geographical conditions never before 

 nor since exhibited on our globe. The frequent alterna- 

 tions of strata, and the great extent of our coal-fields, indi- 

 cate the existence of vast estuaries and inland seas of 

 gigantic rivers and periodical inundations the numerous 

 coal-seams and bituminous shales clearly bespeak conditions 

 of soil, moisture, and warmth favourable to an exuberant 

 vegetation, and point partly to vegetable drift, and partly 

 to submerged forests, to peat-swamps and jungle-growth ; 

 the mountain limestone, with its marine remains, reminds 

 us of low islands fringed with encrinite-banks and coral- 

 reefs, and lagoons thronged with shell-fish and fishes the 

 existence of reptiles and insects tells us of air, and sunlight, 

 and river-banks ; the vast geographical extent of the system 

 bears evidence of an equable and continuous climate over a 

 large portion of the earth's surface ; while the interstratified 

 trap-tuffs, the basaltic outbursts, and the numerous faults 

 and fissures, testify to a period of intense igneous activity 

 within the same areas, to repeated upheavals of sea-bottom 

 and submergences of dry land. All this is so clearly indi- 

 cated to the investigator of the carboniferous system, that 



* Advanced Text-Book of Geology. 



