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Topographically the area consists of three well-marked divisions. Of these the elevated undulating plains, occupied by the metamorphic rocks, cover by far the greater part of the area.
The other two divisions are the low
lying alluvial plains of Gujarat on the west and the western edge of the Malwa plateau, rising to an elevation of about 1,500-1,700 feet above sea level, on the east.
The topographical aspects of this portion of the area vary widely from place to place. The extensive metamorphic region is essentially a much eroded peneplane and presents a diversified countryside consisting of rocky hills, long, straight or sinuous ridges alternating with narrow valleys or flat alluvial plains.
The topographical variations are directly referable to the lithological differences in the constituent rocks of the areas concerned.
The phyllites and schists generally form soft and crumbling outcrops giving rise to rolling hummocky topography. The valleys and plains are mainly occupied by such softer rocks, prone to be buried under the soil derived from their own disintegration. The extensive lands sketchily cultivated by the Bhils, and often dotted with low hills or discontinuous ridges, furnish the best illustrations.
The quartzites associated with the phyllites and schists, from their superior hardness, withstand weathering better and thus in places form steep, narrow ridges, often with characteristically serrated tops, arranged along the strike.
Remarkable instances of such ridges are seen in great abundance in the central tracts of Bariya State, where the chains are symmetrically sinuous in their extension, showing a remarkable parallelism in their strike.
Farther to the north and north-west, in Sunth, Sanjeli, Lunavada and Kadana States, innumerable chains of steep continuous ridges, often running in parallel and sinuous strikes, alternating with narrow, low-lying, well-watered valleys, have imparted a picturesque variety of scene to the central hilly region of the area.
Along the north-western frontier of Lunavada State, where it abuts against Balasinor and Mahikantha States, the country abounds
with straight, parallel ridges, with a general north-east and southwest strike. These vary considerably in length from mere ridgelets not more than a mile in length to chains extending over fifteen to twenty miles. Their width is also variable from place to place along the strike. Although seldom rising more than 300 feet above the ground level, these ridges, in their steep and straight attitude in the midst of the surrounding flat or hummocky country, form very striking features of the local landscape.
The Southern Rajputana States of Dungarpur and Banswara, forming the northern portion of the metamorphic area, show characteristically uneven topography, owing to an irregular assemblage of numerous hills and ridges not generally attaining any great relative height.
But for a rocky belt along the northern frontiers of the States of Chhota Udepur and Alirajpur, the metamorphic area in the south has generally a more even topography, being less frequently interrupted by relict ridges of harder rocks.
Stretching north-west and south-east across the Godhra taluka of the Panch Mahals district an extensive tract of a typical granite country borders the metamorphic area on the west for a length of nearly fifty miles. It has an average width of about ten miles. The area is characterised by a general flatness, the monotony of which is broken by occasional mounds and detached ridges rising from the undulating plain, often to an altitude varying from 450 to 550 feet above the general level of the country.
Several steep-sided and almost flat-topped elevated tracts form distinctive features of the landscape in certain parts of the Panch Mahals district and its neighbourhood. The margins of these miniature plateaux have a general north and south trend, but in detail they are extremely irregular. These highly indented tablelands evidently represent outlying portions of the Malwa plateau, the western edge of which is only a few miles to the east.
A strip of the western border of this historic plateau is included in the area under review. It is an elevated tract varying from 1,500 feet to 1,700 feet in altitude, but appearing to the eye to be of almost perfect flatness, except where low trap hills rise from the uniformity of black cotton soil, derived from the dark Deccan trap lava, the solid rock of the plateau.
At its western edge the plateau drops sharply and gives place to a wilderness of steep, stony ridges and hills. The plateau is highly indented along this entire length. Long, narrow tongues of land stretch out from the main mass and detached conical or tabletopped hills, often rising as high as the plateau itself, fringe the margin.
The normal level of the unconformity between the metamorphic rocks and the overlying trap is about 900 feet; the metamorphics pave long inlets along the bottoms of the valleys in the margin of the Malwa plateau wherever the erosion has gone deep enough to reach the level of the unconformity.
The western flank of the area under review shows a more or less continuous alluvial belt extending southward from Idar State across the eastern tracts of the Ahmedabad and Kaira districts to the north-eastern regions of the Gaekwar of Baroda's territories. But for a few conspicuous outcrops of the Deccan trap and the ancient metamorphic rocks rising like hilly islands through the alluvial belt near its eastern margin, the country appears to be a dead flat. The eastern margin of the alluvial belt is marked by a series of embayments of alluvial tracts alternating with peninsula-like protrusions of the metamorphic area. Evidently this represents the eastern frontier of the coastal band of alluvium formed by the detrital deposits brought down by the rivers of southern Rajputana, Gujarat and the western slopes of the Malwa plateau.
The entire body of the effluent surface water of the area finds its way ultimately into the Arabian Sea through three distinct river systems, namely the Sabarmati, the Mahi and the Narbada.
The mighty Mahi, with its innumerable tributary streams draining the western margin of the Malwa plateau as well as the metamorphic and the alluvial tracts, is par excellence Mahi system. the river of the area. Rising in the Malwa plateau, the river follows a general north-north-westerly course till it reaches the metamorphic tracts at the southern frontier of Banswara State in southern Rajputana. From there it flows northwards up to the northern limit of the State and then turning west
ward forms, for a few miles of its course, the natural boundary between Banswara and Mewar. Here the Mahi is joined by the united streams of the Som and the Jakham, two important rivers of southern Mewar. Hereafter the Mahi follows a general southwesterly course diagonally across the area and finally flows into the Gulf of Cambay.
Of the other tributary streams of the Mahi, the Anas and the Panam are the most important. Both these streams have their sources near the south-eastern corner of the area under review. With an average height of about 1,200 feet above sealevel, this tract forms a small local watershed. On its north the country slopes northwards and the area is drained by many tributary streams of the Anas. The Anas continues its northerly course through the western tracts of Jhabua State and finally falls into the Mahi after attracting the entire drainage of the eastern talukas of the Panch Mahals district and the southern tracts of the Banswara State. On the west of the highland the Panam starts on its westnorth-westerly course and rapidly gains in volume and importance by absorbing the streams of the northern frontier of Alirajpur, and of the southern tracts of Bariya. West of Devgad-Bariya (22° 42′ : 73° 53′) the Panam takes a definite northerly turn and ultimately flows into the Mahi near Lunavada (23° 8': 73° 37′). The country west of this section of the Panam slopes steadily towards the west. The western talukas of the Panch Mahals district are thus drained by another series of tributary streams of the Mahi having a general westerly course. The Kun, the Mesri, the Goma and the Kerad are the most notable members of this series.
The north-eastern tracts of the area are drained by several important tributaries of the Sabarmati river, which flows through Idar State just beyond the western boundary Sabarmati system. of the area under review. Of these tributaries the Hathmati, the Meshwa, the Majham and the Vatrak are the most noteworthy. Flowing south-westerly along strike valleys they have more or less parallel courses within this area.
The southern portion of the area is drained by the tributaries of the Narbada, which runs its westerly course just outside the southern boundary of the area. A belt of
Narbada system. rocky country, beginning from from the southwestern extremity of the Bariya State and stretching east and west across the entire width of the metamorphic area, forms the water
parting between the Mahi and the Narbada systems of drainage. The entire body of effluent water of the southern Rewakantha States finds its way to the Narbada through its important northern tributaries, the Orsang, the Aswan and the Men.
A considerable diversity of climatic conditions is experienced in different parts of the area.
The elevated margin of the Malwa plateau is fairly cool except from the beginning of April to the setting in of the rainy season in June. During these months the area is swept by persistent, dry, hot, west winds. The rainfall is moderate, being 30 to 40 inches annually. The cool season lasts about four months, from the beginning of November to the beginning of March. The atmosphere during this period is clear and dry and the climate is healthy.
The northern tracts of the area under review, consisting of the Mahikantha States and the Southern Rajputana States, enjoy a fairly healthy climate. The division of the year into a hot season, a rainy season and a cold season holds equally good in this part as on the plateau margin. The first and the last, however, are more contrasted, and the annual rainfall is heavier in this area.
The central belt of the area is subject to considerable variations of temperature. Periods of severe cold occur between the months of December and January, frosts often damaging the crops and at times ice forming on shallow pools. During the summer months, again, the heat is often very intense. The average rainfall is about 30 inches. The rainy season is hot and close. The climate is not healthy within this belt. Some of the forest-covered tracts of the Eastern Rewakantha States are unhealthy during the post-monsoon period of the year.
The climate of the southern belt is decidedly moist in comparison with that obtaining in the north. The average rainfall is about 50 inches. Dense teak and mahua forests with wild creepers and grassy undergrowth often cover much of the billy tracts. These prevent free and speedy evaporation of water and keep the atmosphere moist and unwholesome. The cold in January in these parts is very severe, and the heat in May equally so.