Vol. 61 Eeid: The Elastic-Rebound Theory of Earthquakes. 441 



case the scarp was merely the surface indication of the general 

 movement on an underlying fault. 



On January 23, 1855, a severe earthquake shook the region 

 about Wellington, New Zealand. A very interesting account of 

 the changes produced at the time of this earthquake is given by 

 Lyell, from which the following is taken. 



Wellington lies near the southwestern corner of the peninsula 

 which puts out from the northern island and is hounded by 

 Cooks Strait. In the middle of this peninsula lies the broad, flat 

 Wairarapa Valley, trending northeast and southwest. It is 

 bounded on the northwest by the Remutaka Mountains and is 

 separated from them by a great fault. These mountains extend 

 further south than the plain and form the western side of 

 Palliser Bay. After the earthquake, it was found that the moun- 

 tains along the line of the fault for a distance of about ninety 

 miles had suddenly risen nine feet and large fissures appeared 

 between the rock and the soft material of the plain. An engineer, 

 who was engaged at the time in making a road along the side of 

 Palliser Bay, found clear evidence, by the height of a line of 

 shells clinging to the rock, of the elevation of the mountains, hut 

 apparently no evidence was found of a counter movement in the 

 plains. This, however, is not surprising, as the slight variation 

 in slope, which alone could have shown a depression of the plains, 

 would easily have eluded detection ; and, moreover, the softer 

 material of the plains may have been dragged up by the rods:. 

 The northwest coast of the peninsula, about twenty-three miles 

 from the fault-line, experienced no elevation, but Port Nicholson, 

 about half-way between the west coast and the fault, was raised 

 about four feet on its western and five feet on its eastern shore. 

 Lyell looks upon this variation in elevation of the land at the time 

 of the earthquake as showing how the strata may be tilted by 

 varying amounts of elevation, but I think we are justified, with 

 our present knowledge, in looking upon this as an example of 

 elastic rebound, and not necessarily a step in the general tilting 

 of the rocks. 



New Zealand is a land of many faults. They have been more 

 thoroughly studied in the South Island, where they have very 

 materially influenced the topography of the region. Indeed, the 



