VERTICAL OSCILLATIONS OF THE LAND. 57 



The three remaining pillars of the temple of Serapis, near Puzzuoli, on 

 the jNIediterranean shore, with their moUusean borings and the marine 

 deposits in which tliey were half imbedded, yield a record of vertical 

 oscillation tlirough a range of more than a score of feet within half a 

 millennium ; 3"et even in this volcanic and earthquake-ridden region the 

 known movement is almost wholly vertical, the slight inclination of the 

 pillars suggesting unequal settling rather than horizontal movement. 



In 1811-'13 the New Madrid earthquake shook the Mississippi valley, 

 with about one-third of our territory. An area of some thousand square 

 miles sank, and much of it was converted into swamps and a part into 

 lakes, while an area of some hundred square miles was lifted athwart the 

 great river, temporarily reversing its flow and forming other lakes. The 

 downward movement has not been measured, but must have amounted 

 to some feet or yards over thousands of miles. The relative upward 

 movement in the lifted area averaged 15 or 20 feet; yet there is no record, 

 historic or geologic, of horizontal movement other than that of the walls 

 of fissures and of the landslips along the river bluffs. 



These are but instances which might be multiplied indefinitel}'. On 

 every continent some coasts are found to be sinking or rising with respect 

 to tidelevel, and after most great earthquakes the land is lower or higher 

 than l)efore. It is the teaching of common observation by laymen, as of 

 refined observation by surve3"ors, that the coast changes secularly during 

 generations, spasmodically during earthquakes, and with every step in 

 the refinement of observation the number of shifting shores is increased. 

 The shifting of the shore is not, indeed, in all cases traced to corporeal 

 movement within the earth, yet in some cases the connection has been 

 established, and with ever}^ advance in the progress of scientific inter- 

 pretation the numljer of such cases is augmented ; but in every case, on 

 every shore of every continent on the globe, the earth movement is found 

 to be chiefly or wholly vertical, only subordinately if at all horizontal. 

 So it is the common experience of man throughout the world that the 

 observed earth movements are essentially vertical. 



MOVEMEXTS IXFERRED FROM SHORELINES. 



The Scandinavian coast is girt with ancient strands in wliich sea-shells 

 of living si)ecies are found, and these strands are interpreted by the lay- 

 man and tlie learned alike as the work of the waves when the land was 

 lower than now ; yet there is nothing to indicate and every thing- to dis- 

 prove that the land shifted laterally as it lifted vertically. Minnesota, 

 North Dakota and Manitoba are traversed by regular l^anks recognized 

 by all students as the sliorelines of the ancient lake Agassiz, which was 

 bounded on the north by the Pleistocene ice. Evidently these shore- 



