Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

K. N. Prudhvi Raju ¹, R. Vaidyanadhan ¹

Affiliations
1 Department of Geography, Andhra University, Waltair, IN

Abstract

The major geomorphic units of the town of Visakhapatnam are the hill slope elements of free face and debris slope, along with piedmont fans, colluvium and pediment. Waltair Uplands are mainly made up of small detached hills, large accumulations of red sands, often dissected into miniature badlands, and patches of dune sands. Laterites are present both as altered product of hard rock as weIl as colluvium. The coastal zone contains stacks, wave-cut platform, beach and sand dunes. A study of logs of more than 1000 bores put in the tidal basin and features reported and observed here and elsewhere along the coast indicates that during the commencement of Holocene (since 10,000 years B.P.), the sea level might have been about 7 metres higher than the present sea level before it went down to as low as 25 metres and rising again to the present level.

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K. N. Prudhvi Raju ¹, R. Vaidyanadhan ¹

Affiliations
1 Department of Geography, Andhra University, Waltair, IN

Abstract

Study of aerial photographs of an area of about 2000 sq km around Chintapalle in Visakhapatnam district of Andhra Pradesh, shows that broad structural trends are clear only where there are no laterite caps. The lateritic cappings show off on higher altitudes with light tone and generally across structural trends. The cappings, aligned ENE-WSW with a general altitudinal accordance, are suggestive of their occurrence over remnants of a single planar surface. The criteria identified may be applicable elsewhere in the Eastern Ghat terrain for locating lateritic cappings. Such an exercise appears vital in the present context, as many of the laterite caps of the Eastern Ghats are proved to be good bauxite deposits.

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K. N. Prudhvi Raju ¹, R. Vaidyanadhan ¹

Affiliations
1 Department of Geography, Andhra University, Waltair 530003, IN

Abstract

The terrain between the Godavari river in the south and the Mahanadi river in the north, comprising about 50,000 sq. km area forms the study region. LANDSAT imagery and aerial photographs were studied with a view to delineate the fracture patterns and analyse their possible significance. The frequency azimuth rose diagrams of fractures indicate two sets of preferred orientations in ENW-WSW and E-W directions. The possibility of some of these fractures/fracture traces being relatively very much younger to the main Eastern Ghat orogeny is a tentative surmise made from this study. These younger fractures may be related to a cymatogenic upwarp during mid-Tertiary.

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K. N. Prudhvi Raju ¹, K. B. Mahalakshmi ¹, P. V. S. P. Prasada Raju ¹, S. V. B. Krishna Bhagavan ¹, B. David Emmanuel ¹

Affiliations
1 Department of Geography, Andhra University, Waltair 530003, IN

Abstract

The (red) sands at Bhimili with an areal spread of about 7 km² and a height of 90 m above M.S.L. adjoining the beach (sea) has a dome like form. Within this, a typical badland topography has been formed. Three horizons of red, white to brownish and white to yellowish sand occur beneath white sand at the top, The red sands are fine-grained. White to brownish sands are coarse and show partially cemented parallel laminations. White to yellowish sands at the bottom, are coarse and pebbly, and stone lines within them occur inclined towards the sea, with small pebbles to boulders at different heights above M.S.L. and at different distances from the sea. A part of the bed of a major stream in the badland is a uniform wave-cut rocky platform, at a height of 7 m above M.S.L.

The height (7 m) of the rocky platform confirms that the sea level was possibly higher. It is inferred that the white to yellowish sand horizon may be a beach deposit, the white to brownish sands to be coalesced dune deposits and the red sand to be of aeolian nature. Statistical values substantiate mixed populations in the dune environment.

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K. N. Prudhvi Raju ¹

Affiliations
1 Department of Geology, Banaras Hindu University, Varanasi 221005, IN

Abstract

No Abstract.

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K. N. Prudhvi Raju ¹, Ahmed Raza Khan ², Y. Ramesh ³

Affiliations
1 Dept. of Geography, Banaras Hindu University, Varanasi 221 005, IN
2 School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, IN
3 Dept. of Geography, Andhra University, Visakhapatnam, 530 003, IN

Abstract

About 120 km of shoreline in north coastal Andhra Pradesh on either side of Visakhapatnam is rocky with a number of headlands aad bays. Surfaces and caves in rocks along this shoreline were mapped, to explain their relation to sea level stands of Holocene. The physiographic status of surfaces at several locations was worked out in terms of their number and area versus altitude. The seaward margins of hills mapped at many sites along the southern part of the shoreline show a distinct orientation of the outline and dominance of a class of surfaces different from those along the northern stretch. This variability is attributed to the concentration and release of energy of longshore drift and to the variable orientation of the shoreline. Surfaces between elevations of 5 and 1 metre above msl dominate the shoreline. The geomorphic characteristics of these surfaces conform well with those of the storm wave platforms. Sea caves are very few and are associated with either horizontal and/or inclined joints or foliation planes. The 'inactive' cliffs with their toes at about 2 metres above msl along with rocky floors/surfaces with sand cover, point to a sea level stand of 1.00-1.50 metres above the (present) mean low tide level (mltl).

Keywords

Geomorphology, Sealevel, Visakhapatnam Coast, East Coast, Holocene, Andhra Pradesh.

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