MICHIGAN ACADEMY OF SCIENCE. 47 



revealed by the walls of this fissure was in one place no less than 33 feet, but 

 it changed most abruptly and frequently. Where the upthrown side of the 

 fault cut the course of the river on the down stream side, the waters w^ere 

 impounded into a lake, but otherwise a waterfall resulted. Sometimes the 

 fault was double, and examination of a ledge of rock 200 feet distant 

 from it showed that adjustments amounting to several inches had occurred 

 on many of the vertical fissures by which it was intersected. Throughout 

 movements appeared to have been upon essentially vertical planes of 

 fissure. 



At places along the course of the Chedrang fault the ground w^as tilted for 

 a considerable distance in the direction of the course of the fault, and in 

 some cases small lakes resulted from this cause. A roughly cubical block 

 of granite 40 feet long, 30 feet wide, and 30 feet high, which had lain across 

 the course of the fault, had by the movement upon it been completely over- 

 turned. Elsewhere in the vicinity large boulders were seen to have been 

 lifted out of their hollows, projected for a considerable distance, and left in 

 some instances overturned with the dirt still adhering to them. 



In the report upon the district the name fracture is given to the numerous 

 visible fissure planes on which no observable vertical displacement, or at 

 most a ver}^ small one, could be made out. Of these there were hundreds 

 observed, the largest of which became known as the Bordwar fracture. This 

 fissure was followed for about 7 miles in a straight line as a crack in the hard 

 gneiss rock, and showed in places a few inches of displacement. Its course 

 could, however, be easily followed by overturned trees, broken bamboos, 

 land slips, or as a small ditch in the surface of the ground. 



Important changes of level of great blocks of country w^ere clearly shown 

 by the alterations in the aspect of the landscape. Ranges of hills which be- 

 fore had not been visible from certain points, now for the first time came into 

 view, while others had disappeared. In at least one instance some measure- 

 ment of these changes was carried out. So soon as it was noted that the 

 changes had taken place, lines of sight to definite points in the landscape 

 were determined through the nailing of boards to stout posts. Later obser- 

 vations along the same lines gave some measure of the subsequent changes 

 in level. Shortly before the earthquake, a primary triangulation of the 

 district had been " carried out, and a resurvey made subsequent to the dis- 

 turbance revealed changes in elevation of stations by as much as twelve feet, 

 and of location by about the same figure. 



Though the most destructive shocks arrived during the first few seconds 

 of the disturbance, those which immediately followed were heavy enough 

 to have caused great damage had not all structures been already leveled. 

 Shocks of lesser intensity were felt for more than a week, but these gradually 

 faded away. At a point located near the great Chedrang fault, it was noticed 

 that the surface of a glass of water did not come to a rest for more than a 

 week after the disturbance. Observations proved, however, that after shocks 

 were less numerous in the vicinity of the faults than elsewhere within the 

 affected region. When the shocks had ceased to be felt as waves they con- 

 tinued to be perceived as low rumbling sounds. In this period observations 

 extending over twenty-three hours furnished a record of 48 separate disturb- 

 ances, only 7 of which were accompanied by sensible shocks. 



The description of this earthcjuake has placed before us the more import- 

 ant characteristics of large earthquakes. A great earthquake affecting es- 

 pecially the floor of the ocean would have differed by producing a great 

 wave, such as has generally been erroneously designated a tidal wave. 



