416 TRANSACTIONS OF SECTION C. 



' Laurentiaii ' granites and gneisses, were greatly denuded before the lowest 

 Upper Huronian (Aniniikian) strata were laid down/'' This renders the first 

 time-interval here given of very little value, and its resemblance to the third 

 interval seems a matter of mere coincidence. 



Interval from Middle Huronian to Caledonian (Lower Devonian) folding, ( ?) 122 



units. 

 From Caledonian to Armorican (latest Carboniferous) folding, 51 units. 

 From Armorican to Alpine (earliest Pliocene) folding, 127 units. 



Our search for a rhythm is complicated by the occurrence of more localised 

 movements of considerable intensity at intervening geological epochs. The 

 Caucasus, for instance, became strongly folded towards the close of the Jurassic 

 period, when western Europe responded by a gentler grounds well. The 

 Cretaceous beds on the flanks of the Harz Mountains were upturned in early 

 Eocene times, when our English Chalk also came within reach of denudation. 

 Heralds of this unrest may perhaps be seen in the vast outpourings of lava 

 in central India towards the end of Cretaceous times ; and it is clear that we 

 must take into account such igneous upwellings, and also the occurrence of 

 down-sinkings of large areas, when drawing up a history of energy within the 

 earth. 



As already observed, this energy seems effective enough at aU epochs. The 

 Armorican folding was accompanied by immense upwellings of molten matter 

 from the depths, and the features of crust-weakening and absorption seem to 

 have rivalled those that we can study in the basal sections of Archaean 

 mountains. The Alpine movements were pi-obably associated with equally 

 intense igneous action, the extent of which will not be revealed until the present 

 destructive phase of the Huttonian cycle is complete. 



The imminent menace of crustal changes was brought home to us during the 

 terrible period from April 4, 1905, to January 14, 1907, the final twelve months 

 being marked by a veritable earth-storm." Three years had elapsed since the 

 catastrophic events of Saint Vincent, Martinique, and Santa Maria of Guate- 

 mala. On April 4, 1905, 20,000 persons perished through an earthquake in the 

 Kangra Valley, on the flanks of the central Himalayas. On September 8 

 destruction was carried through Calabria. On January 31, 1906, the Colombian 

 coast suffered from sea-waves flung upon it -by the Pacific floor, and in March 

 and April the unrest was manifested on the other side of the basin in Formosa. 

 From the 4th to the 12th of April, Naples was endangered by one of the most 

 serious eruptions of Vesuvius, which reduced the mountain by 500 feet and 

 formed the present crater of e.xplosion. On April 18 San Francisco was 

 wrecked in sixty-five seconds, and the fires that broke out in the shattered city 

 completed its destruction in five days. On August 16 Valparaiso and Santiago 

 similarly suffered, and sea-waves signalled the earth-movement seven thousand 

 miles away on the margin of Pacific isles. On January 14, 1907, the year of 

 earth-storm closed with the ruin of Kingston in Jamaica. 



The last great storm of mountain-folding, that which reared the Cainozoic 

 ranges and marked out the edges of Eurasia and America, seems still to produce 

 symptoms of unrest. Geologically speaking, however, we are near enough to 

 the Tortonian epoch to look forward with some confidence to a quiescent p'hase. 

 But some day, in its due season, the earth will once more be active. When that 

 time comes, no ingenuity of man will suffice to meet it. Earthquake after earth- 

 quake, mcreasing m intensity, will probably have driven the population to a 

 distance from the threatened zone. Concentration of the folding along a par- 

 ticular earth-line will limit the region of absolute destruction; but the 

 undulations spreading from it, in response to the heavings of the chain, will 

 otter sufficient chances of catastrophe. In the case of our youngest mountain- 



" A. P. Coleman, Presidential Address to Section C, Re-p. Brit. Assoc, 1910, 

 p. 598. '■ ' 



" The details are' summarised in G. A. J. Cole, The Channcful Earth (1911), 

 pp. 195-203. ■' ' \ h 



