16 : E. C. ANDREWS, 
way of New Britain and New Ireland,’ Samoa, Tonga, and 
far to the east of New Zealand, beyond which, to the south, 
the Pacific has not been proved as yet to contain Ocean 
Trenches. 
This belt of deeps marks the margin of the Eastern or 
Main Pacific Ocean. The,Tasman Sea which separates. 
Australia from New Zealand, is a deep bay or inlet of the — 
Pacific, and is, moreover, of great geological antiquity.’ 
Of these, all the greatest deeps are confined to the western 
side of the Pacific, and no “‘ trench”’ is known to exist in 
the portion of the ocean lying between latitude 35 degrees. 
South and Antarctica. 
(b) Zone of Harthquakes.—Zones of maximum earth 
quake phenomena are arranged immediately on the inward, 
or continental, side of the Ocean Deeps. The Tethyan 
interference is a noticeable feature in this connection and 
in the case of the Ocean Deeps. 
This zone appears to pass through the great ““deeps”’ of — 
the Heeckel-Milne Edwards Group, thence along the coastal 
strip from Honduras to Alaska. To the south of Alaska 
and the Aleutian Islands it broadens and passes through 
the island arcs of the Western Pacific to New Zealand. 
The great Tethyan girdle of earthquakes forms an inter- 
ference with the Pacific girdle, the ocean trenches follow- 
ing the outer edge of these zones where they are confluent. 
F. Omori’s work? is of great assistance in this connection. 
(c) Volcanic Rings or Belts.—Volcanoes are developed 
in the same great region as the “‘ocean trenches”’ and the 
main earthquake zones, but they lie within rings situated 


+ The Planet Deep (30,000 feet) here lies on the concave or inner aspect 
of the Island and not on the convex or outer one. 
2 E.C. Andrews. Structural Relations of Australia and New Zealand. 
Journal of Geology, 1916. 
®* Bull, Imp. Earthq. Inst. Commission, Vol. I, 1907, Tokyo, Japan. 
