292 T ransactions. 



and explanation of the mode of origin of the great Marlborough conglome- 

 rate as developed in the Dee and Mead Gorges. My own publications on 

 this area comprise some brief observations in the Annual Reports of the 

 Geological Survey for the years 1912 and 1913, a paper on the petrography 

 of the intrusives of Mount Tapuaenuku (1913b), an account of the oil- 

 prosj)ects of the Benmore district (1915), a description of the Amuri 

 limestone and flint-beds as far south-east as the Dee Gorge (1916), and a 

 classification of the Clarentian rocks at Coverham (Woods, 1917). 



The fossils collected by Dr. Cotton and myself from the Clarentian 

 beds, as well as the earlier collections made by McKay, have been described 

 in detail by Woods (1917), who has demonstrated the Albian age of the 

 beds below the flint-beds, and has thus added a new interest to the geology 

 of the area. 



Although the area covered by my visits is much smaller than that 

 traversed by McKay, whose reports cannot, therefore, be superseded, there 

 are several reasons why a new account of the geology of the area should be 

 presented. Both from a structural and from a stratigraphical point of view 

 the district has become a classical one for New Zealand geology, and a more 

 succinct account is desirable. McKay's descriptions both of structure and 

 of stratigraphy are in the main accurate, but are couched in obsolete 

 terminology as regards the physiography, while the stratigraphy is inter- 

 preted in terms of the classification then adopted by the Geological 

 Survey, a classification which has now been universally discarded. In 

 particular, is it vitiated by the false correlation of the Cretaceous rocks 

 below the flint-beds (Clarentian) with those of Amuri Blufi (Piripauan), 

 and this has at times led him to an unbalanced description of the rock 

 sequence, emphasis being placed upon beds which are only locally developed 

 and of relatively small importance. In making these criticisms I do not 

 wish them to detract in any way from the great merit which I consider 

 attaches to McKay's work. His report of 1886, although long neglected 

 by other geologists than Hector, marked a new epoch in New Zealand 

 geology by its recognition of the late Tertiary age of the Kaikoura 

 Mountains, and must always remain a classic. 



The area covered in this paper is so great, and the country so broken 

 and difficult of access, that a complete survey would occupy more than 

 one season of continuous work, and many years must elapse at the present 

 rate of progress before the district can be worked out in detail. The 

 observations both by McKay and by Dr. Cotton and myself can be looked 

 upon only as reconnaissance, and, natm-ally, we have visited somewhat 

 different ground, and devoted greater attention to different parts of the 

 area. There are many new observations, therefore, to be placed on record. 



General Account of the Geology and Physiography. 



Both from a stratigraphical and a physiographical point of view, the 

 rocks of the area may be divided into three main groups, as shown in the 

 following table. McKay did not explicitly recognize this threefold division, 

 and that part of his classification which relates to the present area is 

 appended in the table. Between his Pliocene and Cretaceo-Tertiary groups 

 he interpolated Miocene and Eocene from neighbouring areas. With the 

 exception of the supposed Pliocene conglomerate, however, he implicitly 

 recognized the unity of the middle group of rocks by describing them 

 together under a special section of his first report (1886). 



