378 



THE GEOLOGIST. 



Here allow me to remark that gypseous deposits happening to possess a more 

 than very slight degree of solubility, would not entirely sink in passing from 

 the base of decomposing limestone fissures, and there would be formed layers 

 of fresh water on the now concentrated salt (a truth still noticeable at sea), 

 and the supply of gypsum yet going on whilst evaporation from the surface of 

 the fluid layers still 'proceeded, there would thus be formed beds of rock salt 

 which alternate with gypsum. 



During the progress of these changes, abundant herds of chambered nautili 

 and other cephalopods are spoiting in the quiet waters; and whilst the atmos- 

 phere is now becoming purified for the reception of air-breathing birds and rep- 

 tiles, the traces of whose footprints on the sands are even undisturbed by the 

 gently rippling waters, the truly igneous rocks are on the eve of pouring forth 

 their lavas, which (as Po^vnes has shown) contain phosphoric compounds, these 

 being more abundantly required for the purposes of the seed-producing plants 

 and the supply of bone ; and whilst the reptiles of the Lias are by such dis- 

 turbing causes frequently destroyed, and the delicately sculptured trilobites 

 have entirely disappeared, the agitated waters, charged with our bicarbonates, 

 deposit oolitic rocks, by reason of the numerous shifting grains of sand. Just 

 before the close of these commotions there may be remarked another change, 

 resulting probably (as may be clearly shown from causes now operating in the 

 mineral veins of Cornwall and elsewhere), from the accidental presence of fluo- 

 rides in our decomposing limestone strata (comparable, perhaps, to those of 

 Derbyshire with veins of fluor-spar), green compounds, differmg from mere 

 siliceous sand, and somewhat allied in composition to chloritic rocks, mingling 

 their contents with the settling products. And, now again, there is a period 

 of rest, and whilst the draining of an upraised or still existing westward con- 

 tinent is pouring forth torrents of clayey mud, our bicarbonates deposit challcy 

 rock, which, with the immensely numerous remains of microscopic shells and 

 corals, cover the ocean's bed, and at intervals in which organic forms are 

 favourably found for nucleus, there are formed on it siliceous nodules, in a 

 manner similar to that in which the fossil stems of trees silicify, and compara- 

 ble in this respect with the septaria from our shales and ironstone nodules from 

 the Gault. Changes still go on, and during these there forms a separating gulf 

 between our Gaulish neighbours and ourselves, and at the same time sink the 

 basin-shaped foundations for their capitals, and where these now stand, strange 

 pachyderms, huge snakes and crocodiles in groves of palms, with monkeys, have 

 their sway ; but by-and-bye pouring forth of rivers charged with sulphuiic acid 

 from the decomposing iron pyrites of tlie rocks, and similar to the so-called 

 " vinegar river" of Columbia, at the present time, rushing with violence into 

 these, react upon their loose calcareous strata, decompose their shells, and over- 

 throwing the adjacent banks, bury their mammals in a gypseous mass, dislocat- 

 ing their fragile skeletons, and often leaving only parts of them. To such suc- 

 ceed still more gigantic pachyderms, and very soon mammoths, rhinoceroses, and 

 liippopotami, our varied mammals of the caves, with lions, bears, hysenas, 

 wolves, the machairodus, and other flesh-consuming animals fitted to cope 

 with them, hold their reign ; but all this while an elevating action (perhaps 

 resulting from the same causes that overwhelmed the ancestors of these pre- 

 daceous tyrants), has been in operation, raising whole mountam chains — 

 the Alps, and Pyrenees, Carpathians, Himalayas — having their lofty peaks 

 crowned with the nummulitic limestones, and to this again succeeds, through 

 chemically undermining influence upon the rocks, a period of SMdft depression, 

 during which the crags were formed through stormy waters lashed into fury by 

 the raging winds, commencing now to change and modify the tainted air,' and 

 fit it for tlic dwelling of a future human race. 



But during, and, indeed, before this time, the smouldering volcanos have 



