Zanzibar Geology and Hydrography.pdf
of 2
Transcript of Zanzibar Geology and Hydrography.pdf
-
8/14/2019 Zanzibar Geology and Hydrography.pdf
1/2
05/11/2013 Zanzibar Geology and Hydrography
www.zanzinet.org/zanzibar/nature/miamba.html 1/2
View Zanzibar
Album
Zanzinet Forum
Where Zanzibaris Meet
Zanzinet/ Zanzibar/ Natural Resources/ Geology & Hydrography/
GEOLOGYANDHYDROGRAPHY
The Zanzibar archipelago, consisting of the islands of
Unguja and Pemba and several surrounding islets, arepart of the ancient Miocene Rufiji/Ruvu delta. The core
of these islands consists of rocks ranging in age fromMiocene to recent clacareous sediment with limestone of
marine origin that was subsequently more or less
covered by sands, silt and clays brought by rivers from
the East African mainland. The abundance of coral
limestones on both islands is thought to indicate the
possibility that the sea might have covered much of the
islands at some point in time. However, due to periods of
isostatic movement and block faulting over the coastal
Tanzania and offshore zone these islands remained
above sea level as blocks of the original delta.
The islands are about 40 km from the coast of East
Africa separated by Pemba Channel on the north and
Zanzibar Channel on the south. Unguja Island is about
40 km south east of Pemba and about 56 km north of
Latham Island or Fungu Kizimkazi, which is a small un-
inhabited island also part of the Zanzibar archipelago.
Pemba Channel is much deeper and can reach up to 800
m in depth off the continental shelf of the mainland
Tanzania.
Pemba is a simple fault block and rose earlier than
Unguja; it is thuscomposed of lower stratigraphic rocks,
and geologically much older than Unguja.
Topographically, it is a single ridge andwatershedwith a
raised east coast. It is dissected by hills and ridges and
has a marked indented western coastline with low-lying
shore and numerous marine inlets and dense mangrove
forests. The highest point on Pemba Island is at
Siniongoni about 90m above sea level.
Unguja Island is elongate and indented only sparsely
with a stand of mangrove forests much smaller
compared to that of Pemba. Believed to have emerged
from the sea later compared to Pemba, it wasconnected to the mainland of Tanzania as late as during
the beginning of the Pleistocene age. The topography of
Unguja Island is generally flat but with a central ridge
running from north to south whose highest point is at
Masingini about 120m above sea level.
Zanzibar
About
Zanzibar
Archipelago
History
People &
Culture
Economy
Natural
Resources
Education
Unguja Island
Pemba Island
Statistics
Useful Links
http://www.zanzinet.org/zanzibar/nature/nature.htmlhttp://www.zanzinet.org/zanzibar/nature/miamba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/znz_album.htmlhttp://www.zanzinet.org/ulink.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/education/elimu.htmlhttp://www.zanzinet.org/zanzibar/nature/nature.htmlhttp://www.zanzinet.org/ulink.htmlhttp://www.zanzinet.org/zanzibar/stats/takwimu.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/education/elimu.htmlhttp://www.zanzinet.org/zanzibar/nature/nature.htmlhttp://www.zanzinet.org/zanzibar/economy/uchumi.htmlhttp://www.zanzinet.org/zanzibar/people/people.htmlhttp://www.zanzinet.org/zanzibar/history/historia.htmlhttp://www.zanzinet.org/zanzibar/visiwa.htmlhttp://www.zanzinet.org/zanzibar/index.htmlhttp://www.zanzinet.org/zanzibar/nature/miamba.htmlhttp://www.zanzinet.org/zanzibar/nature/nature.htmlhttp://www.zanzinet.org/zanzibar/index.htmlhttp://www.zanzinet.org/index.htmlhttp://www.zanzinet.org/zanzibar/pemba/pemba.htmlhttp://www.zanzinet.org/zanzibar/unguja/unguja.htmlhttp://www.zanzinet.org/zanzibar/znz_album.html -
8/14/2019 Zanzibar Geology and Hydrography.pdf
2/2
05/11/2013 Zanzibar Geology and Hydrography
www.zanzinet.org/zanzibar/nature/miamba.html 2/2
The ocean surrounding Unguja, Pemba and the related
islands consists of a confluence of ocean currents that
culminate into the East Africa Coastal Current (EACC),
which mostly flows northwards but pockets of residual
currents flowing southwards have been recorded. It is
believed that the northward flows are common during
the Southwest Monsoon (April to October) and
southwards flows in the Northeast Monsoon (November
to March).
About Us| Site Map| Contact Us| 2004 Zanzinet
mailto:%[email protected]://www.zanzinet.org/ab_znet.html
