564 Reviews — Prof. J. W. Gregory — The Origin of Fiords. 



away so as to enlarge the valleys. It is contended that the plans of 

 fioi'ds and sea-lochs cannot be explained by glacial erosion, partly 

 because "the course of the fiords is inconsistent with the lines of 

 flow of the chief glaciers " or ice-sheets ; but here the elff cts of the 

 local glaciers may have been subsequently checked by the invasion 

 of the more extensive sheets of ice. Piords, however, are not limited 

 to areas that have been glaciated, and they are not always found in 

 regions where, if due mainly to ice-action, they should be expected. 



With regard to river-action, it is pointed out that fiords are not the 

 outlets of the main rivers, that in fact "their existence depends on 

 the absence of large rivers, which would fill tbem with sediment and 

 give them the form of ordinary valleys by wearing their walls into 

 long, gradual slopes". Here, of course, the geological structui'e and 

 physical features are largely responsible, as in the case of much 

 of the Western Highland area, where the steep slopes and rapid 

 drainage prevent the formation of large rivers. 



The plan of the chief fiord systems of the world is stated by 

 Professor Gregory to be essentially the same. Fiords occur in trough- 

 shaped valleys that are arranged along a kind of angular network 

 caused by intersecting lines of fracture. This structure was produced 

 by the uplift of the areas to form plateaus : disturbances begun in 

 Miocene but carried out mainly in Pliocene times. The areas of 

 hard rocks were then more or less shattered and cleft by cracks, and 

 subsidence took place of belts of country along the fissured grounds, 

 the troughs or deep basins being formed by irregular movements 

 in Pre-Glacial times. The author refers much excavation to the 

 Pliocene period. In any case, if erosion were commenced so early, 

 it was continued during Pleistocene times by glaciers and other 

 agents. 



Here it may be mentioned that in referring to Plymouth Sound, 

 Mr. Clement Reid has remarked that its rocky floor shows a de- 

 pression far greater than we meet with in ordinary Pleistocene 

 valleys, and "represents not improbably a Tertiary basin ".^ 

 Mr. J. B. Hill also, as qiioted by Professor Gregory, has remarked 

 ,concei'ning certain valleys and inlets of Southern Cornwall that " the 

 straightness of some of them, and in other cases their parallelism, 

 suggests that their course has frequently been determined by lines 

 of dislocation or well-marked joints". l)r. Nansen might also have 

 been called as a witness to the influence of earth-movements in 

 Norway. He has stated that "the longitudinal valleys and fiords 

 of the land surface as well as of the sea-bottom outside, indicate 

 a system of ancient folds and perhaps faults, possibly formed simul- 

 taneously with the uplift of the northern Norwegian mountain chain, 

 or the original subsidence of the bottom of the sea-basin outside ".* 

 Earlier observations, however, by Kjerulf, and the more recent 

 researches of Dr. Sederholm and of othei's, receive full consideration, 

 and the main features of the Norwegian fiords are illustrated in 

 admirable photographs by Mr. H. W. Monckton. 



^ Submerged Forests, 1913, p. 84. 



' Norwegian N. Polar Expedition 1893-1896, Scientific Results, vol. iv, 

 p. 56, 1904. 



