IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India, 2002
Among the various depositional landform features the
formation of spit is a significant feature of recent age. Normally
the formation of spit has been attributed commonly to the
movement and deposition of materials by long shore current.
South of Tuticorin coastal area two spit formations have been
observed with 0.75 to 2 km long and tongue shaped. It appears
to have been built by the sediments brought by long shore
current during southwest monsoon. As the Gulf of Mannar is on
the lee of the northeast monsoon, there is no long-shore drift
from the northeast that might be the cause for the inward
curving of this spit (Ahmad 1972). It can be explained that the
Tuticorin spit might have been the result of the long shore
currents during monsoon and the sediments discharged by
Tamiraparani River. Geocoded IRS LISS-III imagery taken in
the year of 1998 has shown a well-developed spit near
Valinokkam (Figure 4a), but the toposheet of the year 1969
does not show any indication of spit. This spit maybe formed
due to the long shore current from south west, probably under
the influence of the south west monsoon. The southwestern
shore of Rameswaram has a tongue shaped spit. SOI toposheet
of the year 1969 does not show any spit but recent IRS LISS-III
imagery (1998) clearly shows the spit (Figure 4b).It may be
assumed that these spits are recently formed. It can be
explained that the Rameswaram spit may have been the result
of littoral current from Palk Bay to Gulf of Mannar during
northeast monsoon period.
Figure 4. a) Spit neat Valinokkam, b) Spit at southwesr of
Rameswaram Island
Beach ridges are moderately undulating terrain features of
marine depositional type, formed during Pleistocene to Recent
age. They are low, essentially continuous beach or beach dune
materials (sand, gravel and shingle) happed up by the action of
wave and currents on the backshore of a beach beyond the
present limit of storm waves or the reach of ordinary tides, and
occurring as a single or as one of a series of approximately
parallel deposits ( Loveson and Rajamanickam 1987).
According to Short et al. (1989), beach ridges are linear sandy-
shelly swash deposits with intervening sandy plain, occurring
parallel or sub parallel to the shoreline formed by periodic wave
impounding action. Well-developed twelve beach ridges are
seen between Mandapam and East of Vaippar River. Almost all
beach ridges in this area are parallel to each other, and cover an
area of 155.49 km? and trend from east to west and northeast to
southwest direction. On the basis of the nature and dispositions
of beach ridges, it can be grouped into (i) Beach ridges south of
Vaigai River, (ii) Beach ridges between Kotangudi River and
Palar River, (iii) Beach ridges between Palar River and Gundar
River, (iv) Beach ridges between Gundar River and Vaippar
River and (v) Beach ridges south of Vaippar River. These
ridges are clearly indicating the emerging of coastal land in
Gulf of Mannar area.
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Swales and backwater zones are seen between Mandapam and
Kottakkarai River. These are branched and arranged in series of
linear patterns and situated almost parallel to the present
coastline. Prominent backwater zones have been observed in
the coastal plains between Valinockkam and Vaippar River,
Mandapam and Southeast of Tiryppullani. The coastal areas
between Mandapam and Tinaikkulam, Valinokkam and
Krishnapuram and North of Terku Mukkaiyur and
Tukukankulam consist of prominent and wide backwater zones.
These three backwater zones are connected by small, linear and
narrow swales to the sea by means of few creeks, which supply
water from sea to backwater channels during high tide. The
basin bed is composed of silt and mud. The adjacent low lying
area, as a part of swale zone is used at present for salt
production.
Mudflat is a flat area containing a fluid to plastic mixture of
finely derived particles of solid material mainly silt and clay
water. They are always associated with silted environments like
lagoons, estuaries and other embankments. Mudflats are formed
by the deposition of fine inorganic material and organic debris
in particulate form. Mud flats are wide expense of deposit of
clay, silt, ooze, etc. It ends in oscillation of a mass of mud near
mouths of estuaries and lagoons. Repetition of these processes
causes the development of mud flats. The mudflats are very
common in Vaippar River mouth, around Valinokkam
backwater lagoon, Kallar River mouth and Gundar River
mouth. The area covered by mudflat has been estimated to be
14.50 km?.
A chain of 21 low islands have been observed along the
offshore region of Gulf of Mannar. They extends from south of
Rameswaram to Tuticorin. All islands are made up of a
calcareous framework of dead reef and sand. They have a low
and narrow sandy coast and some of them have rocky coast.
Around all offshore islands, well-developed coral reefs (Figure
5) have been noticed. Geomorphologically, coral reefs in this
area are of fringing type, though some patchy corals are also
observed in between Appa Island and Pilliyarmuni Island, and
in some areas like Bharathi nagar coast and southeast coast of
Kariya Shuli Island.
Figure 5. Coral reefs near Krusadi Island
Along the rocky beaches, frequent wavecut platforms are
observed. These features indicate marine erosional formative
processes and represent flat to moderately undulating platform,
predominantly made up of beach rocks and sometimes-
calcareous rocks. Wavecut platforms have been observed along
the coast of Mandapam, Ramaswami Madam, Pudumatam,
Valinokkam etc. At Pudumadam coast, hard and tough
sandstone platform occupies the intertidal zone (Figure 6).
