278 C. A. Cotton — Block Mountains in New Zealand. 



Hawkdun Range (fi^-. 18). This scarp forms the northern 

 bonndarj of the Ida depression also. 



The straight front and remarkably ev^en crest of the Hawkdun 

 block have been noted by McKay (1897) and by Park (1906). 

 Professor Park informs the writer that the surface of the sum- 

 mit plateau is strikingly flat and horizontal. 



The Hawkdiin plateau descends south wai'd from an average 

 altitude of 6,000 feet to something over 5,000 feet in a distance 

 of about 12 miles. At its southern end is the dissected dome 

 of Mount Ida, rising 300 or 400 feet above the plateau {^g. 19). 

 It is perhaps a monadnock as suggested by Park (1906, p. 6). 



The boundary between the depi-essions and the northern 

 highland area swings around Mount Ida and extends due east 



Fia. 18. 



Ca.Ci*:t:o,».1916. 



Fig. 18. Maturely dissected fault scarp of the Kakanui block. View 

 looking north across the eastern margin of the Maniototo depression. 



for 10 miles, forming a great reentrant occupied by a portion 

 of the Maniototo depression, though part of the relatively 

 low-lying area along the base of the scarp is occupied by a 

 number of low-lying, subsidiary blocks, now forming uplands 

 of moderate height in which the undermass is exposed. 



The surface of the Hawkdun block slopes gently eastward 

 from the Hawkdun scarp and Mount Ida down to a fault angle 

 over 4,000 feet above sea-level, bounded by the fault scarp of 

 the Kurow and Kakanui Mountains, which faces west-south- 

 west and rises about 2,000 feet higher. Pemnants of the 

 overmass are preserved in this fault angle on the highland sur- 

 face at the locality known as the Mount Buster or Clark's Dig- 

 gings (McKay, 1881, c). 



The Kakanui fault scarp continues south-southeastward (fig. 

 20) and forms for 15 miles the eastern boundary of the Manio- 

 toto depression, having in this portion an average height of 

 5,000 feet above the sea. The great reentrant in the highland 

 rim occupied by a portion of the Maniototo depression is thus 

 completed and the general southeasterly trend of the great 

 scarp is restored. The scarp continues southeasterly to the sea, 



