ROGERS — WESTERN INDIA. 121 
further eastward, in the position of the Greater and Lesser Runns, 
to the west and east of Cutch, and again in that of the country be- 
tween the Lesser Runn and the Gulf of Cambay. In this last-men- 
tioned tract of country, coinciding to a great extent with the black- 
soil belt, there can be clearly traced a natural depression in the 
surface of the country for some twenty miles from the head of the 
Gulf, terminating in a shallow lake of brackish water called the 
Null. This lake, in the rainy season, is probably twenty miles long 
and three or four broad, and finds an outlet for its superfluous 
waters at that season through the Bhogava, which enters the Gulf 
at its north-west corner. Shells of the genus Cerithiwm, an estuarine 
form, are found lying loose in the black soil many miles from this 
point; and the records of the old Revenue Survey of Goozerat state 
that there were formerly found in the Null large round stones with 
holes through them, which had evidently served as anchors for boats 
of some size. In all this we have strong presumptive evidence of a 
connexion between the Gulf of Cambay and the Runns at a compa- 
ratively modern period ; and there is historical and well-known proof 
of the alteration of the level of the larger of these salt flats as the 
consequence of an earthquake in a.p. 1819. May we not, then, 
imagine a time before the great trap effusions of Western India had 
been poured out, when the granite rocks on the west and north-east 
of the Gulf were wave-beaten islets surrounded by the Indian Ocean, 
which then probably covered the whole region up to the Cretaceous 
formations of Central India, at the mouth or one of the mouths of 
the Indus or some corresponding great river? In a report lately 
made by Mr. Blanford, of the Geological Survey of India, the age of 
the great trap formation of the Deccan and Malwa, of which that 
lying on the east of the Gulf of Cambay forms a part, has been 
determined to be between the Cretaceous and the Lower Kocene. 
This conclusion has been come to mainly from an examination 
of the Nummulitic formation between the Taptee and Nerbudda 
rivers. Mr. Blanford has also shown, from an examination of 
these traps and the intertrappean formations of Bombay and 
other places, that there have been not one but many successive 
eruptions and accumulations, probably extending over long periods. 
May it not, then, have been that previously to any of these the 
Indus had, if not its sole, at least its most easterly mouth in 
the Gulf of Cambay? that on the upheaval of the trap the tract 
to the west and south-west of the primary and metamorphic 
rocks to the north-east of the gulf was raised, and has since 
risen gradually so as to throw the course of the river more and 
more to the westward, drying up successively its channels of com- 
munication with the Gulf of Cambay and the Lesser and Greater 
Runns until it attained its present course and exit into the Indian 
Ocean near Kurrachee? If there is truth in the theory that rivers 
running towards the equator from the north and south have a ten- 
dency, in consequence of the earth’s diurnal motion, to wear away 
their western banks, this may have assisted the westward motion 
of the river. Before the final upheaval of trap on the north-east of 
