Chapter I INTRODUCTION Chapter I INTRODUCTION Ge neral : Sindhudurg district is situated in Western parts of Maharashtra State, India. It is bounded by Arabian Sea on the West, on the North by Ratnagiri district, on the East by Kolhapur district and part of Karnataka, on South by the S tate of Goa. Sindhudurg district, which was, till recently, that is May l, 198 1, southern part of Ratnag iri district and forms a part of the region, classically known as the ' Southern Mahratta Country'. It was first studie d by Wilkinson ( 1 8 71) and Foote ( 1876). In subsequent years, sporadic papers, comprising essentially of preliminary r e ports on the Ge ology of r e stricte d areas, h ave b een publishe d. Pascoe (1922) reported the occurrence of Kaolin near Malvan. Iyer (1939) reported the occurrence of clay f rom Vengurla suitable for c e ramic purpose s. Howeve r, n o attempt has been made to study in detail the mineralogy and industrial propertie s of clays exposed in the s e parts. In a n atte mpt to study the clays assoc iate d with g r a nitic rocks, the present investig ation has been undertaken. 2 Location The area covered by the present investigations, about 5,000 sq kms in extent, is bounded by latitudes 15°38' N and 16°42' N and longitudes 73°20' E and 74°15' E. It forms south-west coastal part of Maharashtra and is included within the topographic sheets 47 H/5, 6, 7, 8, 10, 11, 12, 14, 15, 16 and 48E/ , 9, 10, 13 and 14, 47 L/q, 47 I/1, 2. This newly formed Sindhudurg district includes talukas viz. Devgad, Kankauli, Vaibhavwadi, Malvan, Kudal, Vengurla and Sawantwadi, and is bounded by the river Vaghotan on North and the river Tilar on South. The boundaries and locations of taluka places are showin in the location map (Fig .l.l). The taluka places are connected by fair weather motorable roads, and cart-roads and footpaths, connecting many small villages. In general, the Sindhudurg district is accessible by motorable roads from Pune, Bombay, Kolhapur and Goa. ~ Through the small coastal p~ rt of Vengurla, the district is connected by sea to Bombay. In general, the area under investigations is known as a part of Konkan area within Maharashtra State, India. Physiography : The area covered by present investigations can be physiographically divide d into two parts. On the Eastern part, occurs a gentle undulating plain, dotted by granitic 73. 110: r: ·.... ...... , G I p. / ( '( 400 R A i N ,._ ,; ' ) ' ~s N ,- ,...- · ~..,_ , c . "t,.. ;' . ' •'·-, il• __ <'. ) r' l DE LH, ... b . j O ~ ( '- ) / 1..- ./. r-v-. ( I \ ' J ~"IND IA ~ 0 2 4 6 HI L£ S I I I I I I "OHB~[\ / 0:: 0 4 8 K~S - VE~GURLA " ~\ • MAO!¥.. ? 1l ~-, l I \ y _, I c '' . C>- ~ -N l>l KANKAULI '\J' :s. \ y - .... ... ...., G I/ ' I , _ / "' J - < -- ~I - - - U' \ ' .../"' "\ ~ I r,~ .> -.., ·1 J J '-'l ·..> '\., .... _ .[...- .-:_~ (" ' ·---· _r -~_.,.-' KUQAL 0 ,...__,.) ( \ "' /___ ;' LA j -<; ?p, r ............ I .- ) ::::: sY. ' ~' -~ ,---- j - ·'-r . \ / \-r '-­ --- r~ rj J ~ I SOH SAY ) ' . .) ---~ ~ y\ ; '- VUIGURLA<• '$ ... , t"l( ) ':;> V':tl \ rn"P I 7tl) / > ':;> z l Fig .1 -1: Lc. cation - map of Sindhudurg Dis: ric: . 3 boulders (Plate l, photo l) and a few low ridges of Dharwarian rocks (Plate l, photo 2). The Western part has a more rugged topography. It consists of a number of flat topped hills and ridges dissected by a number of small streams. The plateaux of this part are capped by laterite and the ridges are of Dharwarian rocks. The various plateaux rise to different heights varying between 91.4 m to 152.4 m and the highest at about 304.18 m. A number of short and joint oriented Konkan streams roughly parallel to each other, flow cutting across the area in a roughly south-western direction to meet the Arabian Sea (Fig.l.2). Of these streams, the noteworthy ones are rivers Vaghotan, Deogad, Achra Gad, Kalavli, ' ~arli, Terekhal, Vetero and Talawada. The tributery streams of all these rivers show a definite structural control. ,. The rivers are deeply entrenched in the lateritic plateau, which has a general height of 200 m. The valleys are gorge like in which the streams occupy a very insignificant width. The conformity with the topographical types of drainage in the Eastern part is more sparse than that in the Western part. The difference is mainly due to the fact that the Eastern part consists of an undulating plain that is under­ lain by granitic rocks while the Western part consists of NW-SE trending Dharwarian ridges and flat topped laterite .., \ I . ' ,.... ' . - . .} / 16 · ~ ; 30 ' ' 0 2 4 6 HILE S \' /'-. f ---L"I'~ 0 4 B KMS ? IS cP 0 z - '\. ·"' Jrf Fig .1· 2: Dra·mage 4 capped hil}s. The overall drainage pattern is dendritic. In parts, it tends to a rectangular pattern. In conclusion, it may be stated that the development of physiography in the area under study has been considerably influenced by the structure and lithology of the area. Climate and Rainfall : Sindhudurg district being a coastal part of the tropical mons oonal lands of Maharashtra, in general the climate is moist. Climatically, the year may be divided into four seasons i ) The summer season, arrival of which is indicated by the g radual strengthening of the sea breezes as a r esult of increasing pressure g radient. This season spreads over three months - March, April and May with tempera­ ture varying betwee n 25°C and 38°C. The r e lative humidity is within the rante of 55% and 88%. ii ) The southwe st monsoon season from June to September with t emperature within 24°C a nd 30°C. iii) The post monsoon season covering two months of October and November . iv) The winter season is of three months December, January and February when the temperature varies 5 between 20°C and 3l°C. The range of temperature on this coastal land is low, both diurnal as well as annual, in contrast to the range of the plateau. (Ta ble 1.1 ) , temperature on plateau range is 1l ° C to 40 ° C. Thus, the region is tropical monsoonal land. From the point of view of rainfall, the district falls in the belt of high monsoonic rainfall. So the rainfall is plentiful and regular. The monsoon bursts over the district generally by the beginning of June and the rains continue with little intermission till the middle of October. July is the month with highest rainfall when about one- third of the annual rainfall is received. The average annual rainfall as a whole is 2,667 mm (Table 1.1). Previous work There is little published information regarding the geology of the area especially regarding the occurrences of clays in the area covered by the present investigations. As mentioned earlier, the pioneering studies in the Sindhudurg district (South part of old Ratnagiri district) were carried out by Wilkinson (1871) though Malcomson (1837) was first to visit this area and briefly described the sedimentaries, the occurrences of granite, pegmatite. Wilkinson (1 8 71) could not complete his work. His observations are embodied in his publication 'Sketch of the Geolog ical structure of the Southern Konkan'. Tab l e l. l Rainfall a nd Temperature co ndit~on s in Sindhudurg district Taluka Norma l rain- Temperature Available Record of Konkan fall in mm. in °C based ar ea for 50 year s on 193 1-60 ----------------------------- up to 1965 ------------- Years Actual annual Rain- "Max. Min. fall i n Konkan (Coas ta l r egion) ~anka uli 4099 . 2 No t available 1951 2765.0 ~la l van 3154.7 No t available 1956 3625 . 3 Kudal 3082 .0 Not available 1961 3864 .1 53\.;an th·adi 3758 . 2 Not available 1966 2191.1 Ve ngurla 367 1.0 31.2 22 .4 1971 2879.0 Dcv-::ra:0 d 2245 . 9 30 . 5 23 .9 Temperature Record not Avai l able 33 . 2 18. 5 Average Tempe r a ture in Konkan Area . 6 Foote (1876), has incorporated the important observations made by Wilkinson in his memoir on the 'Geological Features of the South Maratha country and adjacent Districts'. In his work, Foote has referred to the older rocks as gneisses and briefly gives an account of the intrusive rocks near Vengurla as porphyritic syenite and hornblende rock . He also refers to small inliers in the laterite plateaux near the coast north of Vengurla. The present area is included in the geological map given by Iyer (1939) in his publication 'The Geology of South Ratnagiri and parts of Sawantwadi State, Bombay Presidency' . He has recorded the presence of gneisses, mica schists, sandstones, laterite, the occurrences of granite, pegmatite and potash feldspars and the ceramic clays formed from them near Vengurla was described by Iyer (1939). Chromatic deposits, occurring around Kankauli, have been briefly described by Ghosh (1934) and Iyer (1939). Kelkar and Patankar (1939) and Kelkar (1950) described kyanite and staurolite bearing schists from the Ramgarh­ Shravan section. Deformed conglomerate occurring in the Gad river valley were described first by Kelkar and Ghodke (l9S~) and later by Powar and Phadke (1972). Sahasrabudhe (1964) has described the Kaladgi rocks of this region and 7 has stressed the unconformable relationship of Kaladgis with underlying Archaean metasediments. The geology, especially the petrological aspects of the different parts of South Konkan, now forming the present Sindhudurg district, is described by many workers.