SUMMARY AND COSCLVHIOSH 390 



underlying oceans and continents, together with hig general conception 

 of a ahesLring fehell and of igneous intrusions along shearing zones is of 

 great assistance at this stage. The heavier blocks would tend to sink and 

 the crests of the lighter blocks would tend to creep toward them. The 

 nature of the pre- Archeozoic shell is unknown, but it is here assumed a« 

 relatively weak — that is, not compacted, as is the present crust of cooled 

 igneous and metamorphic material which forms the nuclei. The s^i- 

 ments of the Archeozoic, which had been buried deeply, formed a zone 

 of flowage w?iich had connection with the surface of that period more 

 readily than it has at present. A creeping, or ^^rock flowage,'* t^jward the 

 great ocean basins is indicated thus, and this would take place in a 

 manner such that the flowage was reflected as undulations at the surface. 

 These undulations were mutually supporting, the vertical relief being 

 slight compared with the horizontal distance between the waves or undu- 

 lations, as in the case of other waves of pulsation. With local relief of 

 pressure, the deeply seated material gave off emanations or discharges 

 which passed through the zones of strain formed and assumed the form 

 of sills and pressure lens€« between tiie bedding and shear planes of the 

 sediments. With increasing strength of the crust at the nuclei, the less 

 deeply seated zones of pressure passed ontward in confocal undulations 

 to the margins of the unstable areas — ^that is, to crustal masses of less 

 strength. Thes« undulations, or mountains and valleys, represent vertical 

 oscillations of material, with crushing of basin margins and slight lateral 

 motion, rather than a transference of large volumes of material over great 

 distances. 



The control of the sinking blocks underlying the Atlantic and Indian 

 cxeans is indicated by the local ridgings of the c-ontinental nuclei as at 

 Scandinavia and the ghats of India. 



To this mountain-making the injection of igneous emanations and the 

 heating of the sinking sediments contributed considerably, but the actual 

 transference of material was confined to zones which were relatively nar- 

 row within each earth imdulation. This action appears to have deter- 

 mined the great folding and mashing of the earlier and middle Cenozoic. 



The formation of the present series of .mountain ranges would appear 

 to be related to a general pull, by shrinkage, of the suboceanic areas, 

 which set up undulations therefrom in the form of complex units round 

 the margins of these suboceanic masses and which were reflected on the 

 one hand backward to the continental nuclei through the zone of flowage, 

 in widening undulations of decreasing strength, and on the other hand 

 upward thence, with an undulatory surface creep toward the oceans. 



