The Indian Ocean - The Spice Islands - The geology of Pemba
Locations
The Indian Ocean - coastal waters
Location map
Introduction
The tropical Indian Ocean is home to the Spice Islands. Characterised by beautiful sandy beaches, fringing coral reefs and coastal mangrove forests, this is a vibrant nursery area for marine life, such as whale sharks, crabs, seahorses and a great variety of fish. The coastal areas are where humans have the most direct impact on the ocean's resources.
The geology of Pemba
Overview
Pemba Island broke away from the African mainland around 10 million years ago. Today, strong currents that cross the Indian Ocean collide with the solid wall of rock that rises 800m from the sea floor at the island's edges. The action of the tides and currents over time have worn away faults in the rock, forming fissures.
The currents, which create the narrow passageways, are rich in nutrients and attract numerous fish species such as the sea goldie, mimic blennies and anemone fish. On the vertical reefs there are creatures that have adapted to life in the shadows. One example is the green tree coral, which unlike most coral contains no algae and so does not depend on sunlight. Like other filter-feeders it takes advantage of the 'fast food' that passes. Some organisms brought in by the currents have travelled thousands of kilometres across the Indian Ocean.
| Importance: | Studying this geological feature can show how tides and currents shape the land and enrich sea life. |
| Dive category: | The fissure is very narrow in places so this dive is only suitable for those with experience of diving in confined spaces. |
| Access: | Several companies offer dives on the west coast of Pemba. Exploring fissures in the underwater cliff is potentially dangerous because of strong currents and steep walls, so this dive is only suitable for those with advanced dive qualifications. |
Interesting for
- An overview of Pemba Island
- Wikipedia's profile of Pemba Island
- Pemba, Tanzania
- Zanzibar archipelago
- Information about the geology and hydrography of Pemba Island from a web forum for Zanzibaris.
- Geology and hydrography
BBC related content
- Oceans presenter biography: Paul Rose
- Oceans presenter biography: Tooni Mahto
- Oceans image gallery: The Indian Ocean - coastal waters
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