File:The Quarterly journal of the Geological Society of London (13889804597).jpg

272 CAPI. p. W. HUTTON Olf THE GEOLOGICAL POSITION
limestone upon which they rest, and the unconformity therefore is
not due to local causes, but is the result of a general denudation.
Amuri. — Here we get another section showing the Amuri lime-
stone covered by the Grey Marl (fig. 5). Dr. von Haast thinks that
Pig. 5. — Section through Amuri South Bluff.
(Distance one mile.)
5 3 1
For explanation see fig. 1.
the Grrey Marl (called Leda-beds) has, at the South Bluff, been
deposited in sequence on the Amuri limestone * ; but he makes a
difference in the dip of the two rocks. For 'in his section he shows
the limestone dipping E. 70°, and on p. 38 of his report he says
that the Grey Marl dips S.E. 48° to 22°. At the same locality I
found, like Dr. von Haast, that the Amuri limestone dipped E. 70°,
and that the Grey Marl in contact with it dipped E.S.E. 45°,
gradually changing to S.E. 15°; thus indicating an unconformity,
although the actual junction of the two rocks was not seen.
According to Mr. M'Kay, a bed of " green-sand conglomerate "
comes between the Amuri limestone and the Grey Marl, which he
supposes to represent the Weka-pass Stone t. He* has no doubt
that all are conformable and belong to one system, but he makes
the Amuri limestone to dip E.S.E. 45° J, and the Grey Marl to dip
S.E. 45° to 15°. He also shows that the Amuri limestone thins out
in a distance of about a mile, from 630 feet at South Bluff to 330
feet at Amuri Bluff, while the underlying beds belonging to the
Waipara System retain their thickness, or even get thicker §. In
a bed of argillaceous limestone with flints, which extends from the
Waipara to Cape Campbell, this rapid local thinning in the middle
of its length looks much like the result of denudation.
^o fossils had been described from the Grey Marl at this locality
when I wrote my report, and I placed it in the Pareora System
(Miocene) because the rocks in the Conway were supposed to be of
that age. Since then Dr. Hector has found Pecten Zittelli and other
fossils in it which would make it probably the same bed as the
Grey Marl of the Weka Pass.

• ' Geological Reports,' 1870-71, p. 37.
  

t This is the " Pucoidal limestone " of Dr. Hector (Geol. Eeports, 1873-74,
p. xi), which he places below Weka-pass Stone (Geol. Eeports, 1877-78, p. 192).
Mr. M'Kay obtained bones of 'Palceeudyptes antarcticus, Huxley, from it.
\ Judging from this dip Mr. M'Kay appears to consider as Amuri Hme-
stone the same beds that I consider to be Grey Marl ; and this may account for
his statement that Pecten Zittelli occurs in the former rock.