70 Geological Society : — 



indeed, either to outliers or disconnected masses, which might be 

 sometimes supposed to have been due to subsequent denudation. 



Sedimentary matter carried by ocean-currents to the profound 

 depths of the ocean subside into these depths beyond the reach both 

 of currents and of wave-action. The downward motion becomes 

 continually diminished, and the particles ultimately come to ab- 

 solute rest, or move through water of increasing density with ex- 

 cessive slowness, so as to cover the ocean-bottom with an incoherent 

 pulpy mass of fluid mud, of great thickness, and less dense for the 

 most part in the upper than in the lower part, — or to form a similar 

 mass of sediment suspended in mid- water. 



It was also pointed out that in the immense period of time during 

 which this sediment is subsiding into the profound ocean-depths and 

 massing itself into a mud-bed, various hydrographical changes might 

 take place and cause new currents to bring different sediments over 

 the same area, which newer deposits would descend into and be 

 mingled with the older precipitates. 



The author proceeded to treat of the effects of an alteration of 

 isothermal surfaces, caused by the interference of this more or less 

 suspended mud- cloud with the conduction of heat from the earth's 

 surface. Consolidation of the lower strata would be caused by the 

 isothermal surfaces below the ocean rising upwards. Currents of 

 heated water, similarly caused, might variously disturb the sediment 

 and give it flexuous stratification. Heated water might be retained 

 in portions of the sedimentary masses, and alter by its solvent 

 power the constituent materials ; or the heated water might be 

 converted into steam, or generate permanent gases, which might 

 derange or alter the suspended material in various ways. If the 

 sediment had not reached the bottom, but formed a freely suspended 

 mud- cloud in mid-ocean, the effect of the interposed bed of fluid 

 mud impeding the upward progress of heat from the lower region 

 would necessarily be to increase the heat of the water below the 

 mud, and thus place the sediment between the upward pressure of 

 the heated water and the downward pressure of the overlying water. 

 The ocean above would cease to derive its usual supply of heat from 

 below, and become climatally altered. The now consolidated mud- 

 bed would of its own weight either sink bodily down, and take 

 different positions according to its consistency and the form of the 

 ocean-bottom, or it would be contorted and broken through from 

 the effect of the accumulated heat below. In tracing the results of 

 this upward pressure and bursting, the author observed that on the 

 enormously thick and partially consolidated stratified mass one or 

 more weak points would admit of the formation of elevated domes, 

 and that from the bursting of one of these domes, in a sea of much 

 greater length than breadth, a vast wave would be propagated 

 through the plastic matter, which would advance and be followed 

 by others less perhaps in degree. As the original wave advanced, 

 the diminishing depth of the ocean would cause the head of the 

 wave to advance with greater speed than its base, impeded by 

 friction on the ocean-floor, and give it its advancing form and a 



