Cotton. — Block Mounfa/ns <nul a " Fossil " Douulafion Plain. 61 



quent streams, descends towards tlie Tasman Sea. Ihe mountain-ranges 

 t)f the middle, <>r Haupiri, block — tliat between the Aorere and Takaka 

 Valleys — appear to liave been carved from a mass which had initially 

 a rough anticlinal nr domed form, its present surface descending towards 

 the north-west, north-east, and east from heights of over 5,000 ft. at 

 the south-western end. The l)lock is perhaps composed throughout of 

 a number of smaller or secondary blocks separated from one another by 

 faults and flexures. This is certainly the case towards the west, where 

 tlie Haupiri block coalesces with tlie Wakamarama block in a region 

 of flexed and broken plateaux known as the Gouland Downs. Tliese 

 plateau surfaces are remants of a stripped, " fossil " denudation plain 



Tasrian Sea 



Fig. 1. — Locality map of northern Nelson. 



wliieh formed the floor underlying a series of marine strata since removed 

 over large areas, but here and there preserved. 



These marine covering strata are weak in comparison Avitli the 

 resistant undei'mass, and so the planed surface of the latter, which 

 ti'uncates indiltViently indurated and metamorphosed clastic sediments 

 -and crystalline limestone of complex structure and also granitic intru- 

 sions, and forms tlie floor upon which the covering strata have lain, 

 survives in favourable situations as a plateau long after the cover has 

 been removed. It has, howevei-. Ijeen desti'oyod, as might be expected, 

 Avhere its attitude favours deep dissection. 



The Takaka Valley fault-angle depression is b(Hinded on the east 

 for twelve miles by an almost undissected fault-scarp nearly 3,000 ft. in 

 height, with a north-and-south trend, which is the western edge of the 

 block forming the Pikikiruna Kange, and which may, therefore, be 



