Cotton. — The Uplifted East ('oast of Marlborough. 287 



With regard to the last point, however, it may be noted that, while 

 along the greater part of the length of the eastern coast subsidence of the 

 region to the east almost certainly preceded the uplifts here recorded, for 

 a short distance southward of Kaikoura off-shore subsidence was more 

 recent, resulting in the formation of a strip of fresh fault coast. The writer- 

 hopes to describe this fault coast in another paper. The boundary between 

 the depressed Marlborough Sounds area and uplifted eastern Marlborough 

 is obscured by the flood-plain of the Wairau River, though possibly it may 

 be seen in the Upper Wairau Valley. 



It may be here noted that, while there is proof that in early Quarternary 

 times the region stood much lower than at present, no evidence has been 

 observed by the writer in eastern Marlborough of a Pleistocene movement 

 of depression* of any consequence. 



It would seem that the Kaikoura orogenic movement was followed by a 

 period of rest, and that afterwards the discontinuous movement of uplift 

 began, which is still in progress. It may be true that during the course 

 of this uplift there have been some downward oscillations ; but, if so, they 

 must be of relatively slight importance in the geological history. 



1. Re.juvexated Topography. 



The Weak Rocks. 



Along the shore of Cook Strait, from the mouth of the Awatere River 

 to Clifford Bay, unconsolidated mudstones and sandstones form the coast. 

 The lower valleys of the Awatere River and the neighbouring smaller 

 streams, the chief of which is the Blind River, are excavated in these beds, 

 which extend up the Awatere a dis- 

 tance of twenty-five miles. The rocks 

 of this area are generally known as the 

 Awatere beds, and are of Tertiary 

 (some of them certainly of late Ter- 

 tiary) age. The extent of this area of 

 very weak rocks is shown in fig. 2. 



A strip of iithologically similar rocksf 

 (nearly all mudstone) forms Cape Camp- 

 bell and the coast for some distance 

 southward, and there is a considerable 

 area of similar weak mudstonef at the Fig. 2. — Map showing the Areal Dis- 

 mouth of the Kekerangu River and ^e^M K ™ E AwatERE BedS 



southward to the mouth of the Clarence. (after c ay;. 



Here the beds stand in a nearly vertical altitude ; in the lower Awatere 

 Valley, on the other hand, they lie nearly horizontally or dip at low angles. 

 The topographic forms developed by erosion are, however, independent of 

 the dip and strike, for the rocks are uniformly very weak, and are in this 

 respect in marked contrast with all the other rocks of the Marlborough 

 coast. In a period barely sufficient to allow streams working on mode- 

 rately resistant rocks to grade their channels the surface of these beds is 

 reduced to mature or even senile relief, and their topography consequently 

 preserves admirably the history of a rapid succession of movements of 

 uplift separated by pauses. Erosion would, however, during a relatively 

 prolonged period of standstill efface the whole record. 



* See P. Marshall, "New Zealand," " Handbuch der regionalen Geologie," vii, 1, 

 p. 47. 



t Not necessarily of the same age as the Awatere beds. 



