Polynesia
381
Cook Islands
MAPS iAd and e
The
Cook Islands are a group of 15 islands, or island
groups, scattered across a wide expanse of ocean.
Descriptions typically divide the islands geographically into a northern and a southern group. The
northern Cook Islands are a group of five atolls and a
platform island. With the exception of Penrhyn they are
located on the Manihiki Plateau. It seems likely that they
formed when this was a shallow volcanic feature and the
atolls have grown up as the plateau itself subsided. Penrhyn.
by contrast, is an isolated feature rising from the deep
ocean. In addition to these islands, Tema Reef is a subsurface platform reef located between Pukapuka and
Nassau Island. Flying Venus Reef is another platform
structure lying on the same seamount as Penrhyn, but
separated by a deep (more than 500 meters) channel.
The southern Cook Islands show a wide range of
oceanic island types. They follow two parallel chains
running from the northwest to the southeast, and they
continue as the Austral Islands in French Polynesia,
terminating in the volcanically active Macdonald Seamount,
probably indicating some form of hotspot origin to the
islands. Palmerston and Manuae are true atolls and Takutea
is a platform island (possibly left behind after the partial
collapse of an atoll structure). Aimtaki is a near-atoll with
one large and two small volcanic islands located in the
lagoon. Four islands. Mitiaro, Atiu, Mauke and Mangaia,
have been described as makatea (fossil reef) islands. They
have a volcanic center with a carbonate rim of reef origin,
now uplifted to some height above sea level. Finally, the
main island of Rarotonga is a high volcanic island (652
meters) with substantial ridges and steeply incised valleys.
Fringing reefs occur around all of the makatea islands and
around Rarotonga in the southern group, although these can
be quite narrow. Reef flats are typically very level with a
hard platform, while the crests are dominated by coralline
algae, and spur and groove formations become characteristic
offshore. The lagoons are highly varied among the atolls.
Manuae, in the southern Cooks, has a very sandy shallow
lagoon. Rakahanga's lagoon is virtually enclosed by islands
and shows very little active coral growth, whereas most of
the other northern islands have relatively deep lagoons
(average depths of over 10 meters) with varying degrees
of reef development. Winslow Reef, in the southern Cooks,
is a shallow platform reef lying nearly 150 kilometers
northeast of Rarotonga and lacking any above-water
structures. Due to their southeriy location, all the Cook
Islands lie in the path of hurricanes and storms, which
typically occur between January and March.
Suwarrow Atoll, an isolated atoll in the northern Cook islands I5TS055-97-58. 19931.
381
Cook Islands
MAPS iAd and e
The
Cook Islands are a group of 15 islands, or island
groups, scattered across a wide expanse of ocean.
Descriptions typically divide the islands geographically into a northern and a southern group. The
northern Cook Islands are a group of five atolls and a
platform island. With the exception of Penrhyn they are
located on the Manihiki Plateau. It seems likely that they
formed when this was a shallow volcanic feature and the
atolls have grown up as the plateau itself subsided. Penrhyn.
by contrast, is an isolated feature rising from the deep
ocean. In addition to these islands, Tema Reef is a subsurface platform reef located between Pukapuka and
Nassau Island. Flying Venus Reef is another platform
structure lying on the same seamount as Penrhyn, but
separated by a deep (more than 500 meters) channel.
The southern Cook Islands show a wide range of
oceanic island types. They follow two parallel chains
running from the northwest to the southeast, and they
continue as the Austral Islands in French Polynesia,
terminating in the volcanically active Macdonald Seamount,
probably indicating some form of hotspot origin to the
islands. Palmerston and Manuae are true atolls and Takutea
is a platform island (possibly left behind after the partial
collapse of an atoll structure). Aimtaki is a near-atoll with
one large and two small volcanic islands located in the
lagoon. Four islands. Mitiaro, Atiu, Mauke and Mangaia,
have been described as makatea (fossil reef) islands. They
have a volcanic center with a carbonate rim of reef origin,
now uplifted to some height above sea level. Finally, the
main island of Rarotonga is a high volcanic island (652
meters) with substantial ridges and steeply incised valleys.
Fringing reefs occur around all of the makatea islands and
around Rarotonga in the southern group, although these can
be quite narrow. Reef flats are typically very level with a
hard platform, while the crests are dominated by coralline
algae, and spur and groove formations become characteristic
offshore. The lagoons are highly varied among the atolls.
Manuae, in the southern Cooks, has a very sandy shallow
lagoon. Rakahanga's lagoon is virtually enclosed by islands
and shows very little active coral growth, whereas most of
the other northern islands have relatively deep lagoons
(average depths of over 10 meters) with varying degrees
of reef development. Winslow Reef, in the southern Cooks,
is a shallow platform reef lying nearly 150 kilometers
northeast of Rarotonga and lacking any above-water
structures. Due to their southeriy location, all the Cook
Islands lie in the path of hurricanes and storms, which
typically occur between January and March.
Suwarrow Atoll, an isolated atoll in the northern Cook islands I5TS055-97-58. 19931.