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Rh however, practically certain from sertions exposed elsewhere-notably that at North Head figured by Dr. Marshall that the oldest rock is the Logan's Point type and that the Signal Hill type, which is closely related to the ancesitie type of the North Head, rests upon it. The intervening basalt and basanite flows are not represented at Signal 1&ill, although a first inspection of the sections exposed along the Main North Road might: lead to the belief that basali intervenes between the flows of the two types of phonolite.

Going up the road from Normanly one passes successively Logan's Point phonolite. basalt. and Signal Ilili trachytoid phonolite. A closer inspection shows that while the basalt overlies the Logan's Point rock, it ako overlies the Signal Hill type ani is continuons with the main basalt- flow which covers the summit of the bill, and has the peculiar distribution to be described later. This mass of basalt evidently filled a depression which existed near the line of junction the two types of photolite, and which may have been the result of crosion, or perhaps was caused by the rapil solidification of the relatively acid phonolite lava. Section No. 1 gives the distribution of these rocka.

In connection with both types of trachytoid phonolite it may be stated that, in places where the rocks are exposed in silu, the cleavage is approximately horizontal.

Above the phonolite of the Logan's Point type there occurs, on the Signal Hill Road, about the 80 ſt. contour-line, a bel of scoria 30 ft. in thickness. From an undeconiposel core in this a specimen of basalt was obtained of a much more acid type than the main basalt-flow which followed it. It is described as luasalt No. 1.

The main basalt-flow, described as basalt No. 1. covers the sumit of the hill, and on the south-eastern side extends down only a short distance. It continues, however, much farther in a north-westerly direction, and to the north extends in a narrow belt across the head of the eastern arm of the North-east Valley towards Mount Cargill. This distribution is very peculiar, and it might be suggested that the basalt covering this area consists of a number of lava-Hows, some of which alternate with flows of trachytoid phonolite. This explanation, however, is not upheld by field evidence. The sections exposed on the Main North Road, and numbered con- secutively 1 to 10 on the accompanving map, are as follows :-

(1.) Direction, N.E. SW. Heint alorr sca-level. 330 ft. Basalt lies horizontally upon Loyau's Point phonolitor.

(2.) Direction. Y.Y.S.E. lleight above sea level, 180 ft. Basalt lies upon tracksioid phonolite (Nional Fill typ«), clipping N.11. 12.

(3.) The section is not dear, but basalt appears to overli Signal Hill phonolite nearly horizontally. Height above sea, 520 ft.

(4.) Direction. X.W.-SE. Height above mea-level. 530) ft. Basalt lies upon Signal Hill phonolite, dipping 12! X.W.

(5.) Direction, X. E.-S.11. Height above sea level, 580 ft. Pasall lies upon Signal Hill phonolite, clipping 4 N.E. The basalt is then con- tinnous for about half a mile.

(6.) Direction. E.N.E.I.N. Heicht above sea level. 750 ft. Basalt lies upon Signal Hill phonolite, clipping W.S.W.89

AL (7) and (8) the sections are not clear, but between these points basalt is continuous.


 * Marshall, "Gieology of Dunedin," Quun. Joum. Geol, You, 1x, 1915.