L - Cochin University of Science and Technology

The continental shelf and its adjoining land of the study area is bordered by
Western Ghats and is influenced by monsoon. The climate is tropical with maximum
precipitation during monsoon and the shelf is floored with different types of
sediments. According to Stewert and Pilkey (1965) the continental shelf in the study
area can be divided into inner shelf and outer shelf marked by the difference in the
topography and sediment type. Studics by Nair (1971) and Siddiquie and
Rajamanickam (1974) have shown that the inner shelf has smooth featureless
topography whereas the outer shelfis fonned by rugged topography.
Width of the continental shelf varies from about 100 km off Suarashtra (Off
Dwaraka) coast (Gupta, 1979) to 280 -300 km wide off Mumbai (Kidwai and Nair,
1972) and this narrows down to about 100 km off Ratnagiri to a progressive
narrowing of 60 km wide shelf off Monnugao (Nair,1975). The shelf off Mumbai is
composed of various features like pinnacles with and without adjacent troughs, which
are usually 1-2 m deep (Nair,1975). In addition to these features a number of large
mound shaped protuberances with a relief of 6 to 8m are also present. In Ratnagiri
the pinnacles and troughs are poorly developed as compared to off Mumbai and
when it reaches Monnugao pinnacles with relatively gentle depression occur on a
slopping shelf. A notable feature is that pinnacles and troughs are most prominent off
Mumbai where the shelf is flat and widest and become relatively subdued in profile
towards south where the shelf is generally half or less than half of width. Wider shelf
OfT Mumbai narrows in Ratnagiri and further narrows southwards.
Many workers have studied the substrata of northwestern region and most of
them pertain to the regional studies including estuaries and gulf regions and a few
studies were carried out in the shelf region to assess the textural characteristics.
Kidwai and Nair (1972) studied the sediment texture and distribution of organic
matter in the NW coast of India (18-22° N) and later, Nair (1975) described the
nature and origin of small-scale topographic prominences on the western continental
shelf of India. Parulekar et al., (1976) studied the sediment texture and organic matter
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