212 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



planned series of such experiments, we might be enabled to trace 

 the gradually disappearing structure of animal remains existing in 

 rocks subjected to fire, into marks wiiich, without sucii aid, seem 

 utterly distinct from that origin ; and that we might thus establish 

 new alphabets with which to attempt the deciphering of some of the 

 older rocks*. 



96. It appears, therefore, that from changes continually going on, 

 by the destruction of forests, the filling up of seas, and the wearing 

 down of elevated lands, the heat radiated from the earth's surface 

 varies considerably at difi^erent periods. In consequence of this varia- 

 tion, and also in consequence of the covering up of the bottoms of seas, 

 by the detritus of the land, the surfaces of equal temperature within 

 the earth are continually changing their form, and exposing thick 

 beds near the exterior to alterations of temperature. The expansion 

 and contraction of these strata, and, in some cases, their becoming 

 fluid, may form rents and veins, produce earthquakes, determine 

 volcanic eruptions, elevate continents, and possibly raise mountain 

 chains. 



The further consequences resulting from the working out of this 

 theory would fill a volume, rather than a memoir. It may however 

 be remarked, that whilst the principles on which it is founded are 

 really existing causes, yet that the sufficiency of the theory for ex- 

 plaining all the phsenomena can only be admitted when it shall have 

 been shown that their power is fully adequate to produce all the 

 observed eifects. 



Addition hi \S^1. 



It appears from the preceding paper, that the joint action of certain 

 existing and admitted causes must necessarily produce on the earth's 

 surface a continual but usually slow change in the relative levels of 

 the land and the water. Large tracts of its surface must be slowly 

 subsiding through ages, whilst other portions must be rising irre- 

 gularly at various rates : some, though perhaps few, may remain 

 stationary. 



It is a curious and an interesting fact, that this geological deduc- 

 tion, derived from pure reasoning, although suggested by the obser- 

 vations made on the temple of Serapis, which was first published In 

 1834^ should soon after have received direct confirmation from an 

 entirely opposite quarter. 



Mr. Darwin, whose voyages and travels extended from 1826 to 

 1836, was gradually accumulating and arranging an immense collec- 

 tion of facts relating to the formation of coral and lagoon islands, as 

 well as to the relative changes of level of land and water. In 1838 



* Some experiments, with this object in view, were undertaken at the recom- 

 mendation of the British Association (see Third Report, p. 479, and Fourth Re- 

 port, p. 576), and portions of rock containing organic remains have already (^1838) 

 been exposed, for above five years, to the heat of the hearth of a blast fnrnace, at 

 the Elsecar Iron Works in Yorkshire, through the permission of Earl FitzwilHam, 

 and at the Low Moor Works, by that of the proprietors. 



