EARTHQUAKES 



289 



^D/LMA 



CfiFDRAA/G fXULT 



erge Poo/ 



e Poo/ 



have been elevated dur- 

 ing an earthquake in 



1835- 



Landslides. — One of 

 the most obvious effects 

 of a severe shaking of 

 the earth is the produc- 

 tion of landslides and 

 the slumping of thick 

 soil which rested on a 

 slope. The hills about 

 Kingston, Jamaica, for 

 example, are scarred by 

 landslides formed during 

 the earthquake of 1907. 

 As a result of an earth- 

 quake in India in 1897, 

 the hills were stripped 

 of their forests by land- 

 slides. This permitted 

 erosion to proceed so 

 rapidly as to overload 

 the streams, with the 

 result that the rivers, 

 instead of flowing from 

 deep pools over rapids, 

 flowed in broad, shallow 

 channels over a sandy 

 floor. An earthquake in 

 Greece in 1870 caused 

 great landslides which 

 dammed up some of the 

 valleys and formed lakes, 

 some of which are still 

 in existence. 



Earthquake Topog- 

 raphy. — A description 

 of the fault rift along which occurred the movement which produced 

 the San Francisco earthquake will serve, in a general way, for all 

 such earthquake faults or earthquake topography. This line is well 



Scale of ff//ez 



Fig. 287. — Map of the Chedrang fault, India, 

 showing the effect of faulting on drainage. The 

 figures show the amount of vertical elevation in feet. 

 The river in places flows along the downthrow side 

 of the fault, and is ponded back in others. The 

 tributary streams also are dammed, forming pools. 

 Waterfalls are formed where the river crosses the 

 fault. In one place the fault runs along the old and 

 now dry bed of the river, while the stream itself flows 

 in a depression on the downthrow side. The large 

 pools are not formed by the fault scarp, but by the 

 reversal of the original slope of the river bed by the 

 unequal elevation of the land, there being no eleva- 

 tion at the pools, but an elevation of more than 30 

 feet above each pool, and a lesser elevation below. 

 (After Oldham.) 



