538 GEOLOGY. 



Present movements. — Critical observations on seacoasts show that 

 some shores are slowly rising and some slowly sinking relative to the ocean- 

 level. We do not certainly know what their movements are relative 

 to the center of the earth ; very possibly all may be sinking, one 

 set faster than the other, the ocean-surface also going down at an 

 intermediate rate. Theoretically, all might possibly be rising, one set 

 faster than the other, the ocean also rising at an intermediate rate, 

 though this is extremely improbable. One set may be actually rising 

 relative to the center of the earth, and the other sinking, while the ocean- 

 level is stationary, or nearly so. This is the way in which we are 

 accustomed to interpret them. A general shrinkage of the earth, how- 

 ever, is probably going on, carrying down land-surface and sea-surface. 

 It has been urged by Suess ^ that the general shrinkage is so great that 

 the local upward warpings and foldings never equal it, and that the real 

 movements are all downward, though in different degrees. This is 

 probably the general fact at least. Over against this is the popular 

 disposition to regard earth movements generally as '^ upheavals.'' 

 There is also a predilection for regarding the rigid land as movmg and 

 the mobile sea-level as fixed. In reality, the sea is an extremely adap- 

 tive body that settles into the irregular hollows of the lithosphere, and 

 is shifted about with every warping of the latter. Whatever change 

 affects the capacity of its depressions affects also the sea-level. If they 

 are increased, the sea settles more deeply into them; if they are decreased, 

 £he sea spreads out more widely on the borders of the land. The one 

 thing that gives a measure of stabihty to the sea-level is the fact that 

 all the great basins are connected, and so an average is maintained. 

 A warping down in one part of the sea-bottom may be offset by an up- 



records are found are cited below: California earthquakes, Perrine, Bull. 147, U. S. 

 Geol. Surv. ; Earthquakes of the Pacific Coast, Holden, Smithson. Misc. Coll., No. 

 1087, 1898; Records of recent earthquake movements in Great Britain since 1890 

 are published by Davison in Quar. Jour. Geol. Soc, Geol. Mag., and Nature; Records 

 of ■earlier earthquakes are found in the reports of the Brit. Assoc. (Mallet), in the Edin- 

 burgh New Philos. Jour., Vols. XXXI-XXXVI (Milne), and in Trans, of the Roy. 

 Irish Acad., 1884 and 1886 (O'Reilly); The Earthquakes of Scandinavia have been 

 recorded in volumes of the Geol. Foren, Forhandl. ; Records of other continental 

 European earthquakes are found in Gerland's Beitrage zur Geophysik, 1895, 1900, 

 and 1901; Neues Jahrb., 1865-71; Zeitschr. Naturwissen. (1884), (Credner); Bericht. 

 k. Sachs. Geolv Wissen., 1889 and 1900 (Credner); Jahrb. Geol. Reichsanst., 1895 and 

 1^97; Tsehermak's Min. Mitth., 1873, and later; Transactions of the Seismological 

 Soc. of Ja^a,ni. An index to these Transactions is given at the end of Milne's Seismology. 

 '- 1 Antlitz der Erde. Vol. 1, p. 136. 



