ЕтхгАү AND McDowarr.—Fossiliferous Limestone at Dowling Вау. 107 
The section along AB indicates the relative position of the beds. 1% 
can be seen that the fossiliferous limestone overlies the Caversham sand- 
stone without unconformity, and therefore, if the age of these beds can 
be determined from palaeontological evidence, a limit is placed on the age 
of the Caversham sandstone. It may be noted also that somewhat similar 
fossiliferous limestones appear among the volcanic rocks of Sandymount, 
on the southern side of the harbour,fand these also appear to be underlain 
by the Caversham sandstone. 
Ofel P Recent Allium Sand & 
Landslip-rubble 
poc Trachytoid Phonolite 
Basalt ( several flows] 
Argillaceous or Calcareous 
B Sandstone & Lmopss Bed 
Ft 
Caversham Sandstone. 
SECTION 
ALONG 
AB 
МАР or FossrLrFEROUS LIMESTONE AT DowrrNG Bay. 
The trachytoid phonolite, mapped as such by Dr. Marshall in 1906, 
has been described for us by Dr. Benson in the following terms: “ Micro- 
scopically this rock resembles the phonolite of Logan’s Point, near Dunedin, 
but has a rather greater grain-size. The dominant mineral is a soda 
sanidine, which occurs in small phenocrysts up to a length of 0-8 mm., and 
much more abundantly in narrow laths in general fluidal arrangement, but 
with sheaf-like radiating groups. No trace could be observed of anortho- 
clase, or, indeed, of any polysynthetically twinned feldspar.  Interstitially 
there is a small amount of zeolite material with bright polarization colours, 
probably replacing nepheline, which latter could not be distinguished in 
