328 ON THE MOVEMENTS OF THE EARTh's CRUST. 



Keferriug for other thiugs to the two memoirs cited aud to my paper 

 "On Variations of the Weather in the course of time" {Letterstedtske 

 Nordisk Tidskrift, 1885, in English, in Fork. Vid. Selsk. i Christiania, 

 1886, No. 8) I will pass on to examine whether there is any probable 

 ground for supposing that the other proposition is also correct, whether 

 it is conceivable that under high latitudes the sea-level rises and sinks 

 with tlie eccentricity of the earth's orbit. 



Great part of the earth's surface consists of strata which still lie un- 

 disturbed in their original horizontal position. These parts are called 

 "tables" by Suess. But in many places the crust of the earth is so 

 traversed by clefts and fissures that it may be compared to a breccia. 

 Fragments are often displaced relatively by thousands of feet. Strata 

 which originally lay horizontally are folded, thicknesses of 7,000 to 8,000 

 feet are bent as if they were straws (Kjerulf, Udsif/t over Norgcs Geologic 

 1870, p. 70). Moreover, the folded strata are upheaved far above their 

 original level. Even marine formations so recent as the Eocene are up- 

 lifted to heights of 21,000 feet above the sea (Suess, Anflitz der Urde, i, 

 p. 5G4). Sometimes they stand vertically, or are inverted, so that oWer 

 strata cover the younger ones. Through fissures eruptive masses are 

 brought forth, and have covered thousands upon thousands of square 

 kilometers. The distribution of land and sea also varies. It is indeed 

 supposed that the great depths of the ocean and the great continents 

 have essentially retained their original distribution from the most an- 

 cient times, but the shore-lines wander periodically to and fro ; and these 

 changes of the earth's surface have taken place from earliest times, and 

 are still in action at the present day. 



Geologists in general seek the explanation of these phenomena in the 

 cooling and contraction of the body of the earth. The earth's crust 

 folds, just as the skin of an apple wrinkles as the apple dries. The lead- 

 ing geologists of the present day adopt this theory, and A. Geikie in his 

 "Text-book of Geology" (London, 1882, p. 287) says truly: "With 

 modifications, the main cause of terrestrial movements is still sought in 

 secular contraction." 



According to this doctrine changes in the crust of the earth are due 

 to the interior contracting more strongly than " the crust," so that the 

 latter is too large for it. Its weight drags it down. By this means 

 great horizontalh' acting pressure is i)roduced in the crust, which must 

 then become folded and cracked in places. The fragments sink down. 

 By this means are formed what Suess has called " Einbrliche." When 

 a part of the crust remains in i)Osition while all around it sinks, there 

 is produced what Suess has called a " Horst." The old theory of forces 



aijhelion. The winter solstice foil in apbelioa (according to CroU) 61,300, 33,300, and 

 11,700 years ago. The middle of the Atlantic period with Bergeniau sea-animals in 

 the Christiania Fjord fell, from the testimony of the peat-mosses 33,000 to 34,000 years 

 ago, therefore in accordance with the period of 28,000 years. 



