150 Mr. Gardner on the Existence of Chalk in Brcutil. 



2d. A deposit of marls, soft and compfact limestones, and lignite, 

 equivalent to the English gait, h. 



3d. A very thick deposit of fine grained, soft, variously coloured 

 sandstone, equivalent to the upper green sand of England, 

 containing Ichthyolites, c. 



4th. The white chalk itself, and flints, occuring in pits e, e, e, par- 

 tially covered by red diluvial clay, d. 



In none of the chalk pits which I examined myself did I find any 

 flints ; but I was informed, that at a considerable distance to the north 

 of Crato, at a part of the Serra called the Serra de Botarite, both 

 chalk and flints are much more abundant than they are near Crato, 

 where they seem to have been nearly washed completely away previous 

 to the deposition of the red clay in which it is now found. 



Since the time that the rocks were first deposited at the bottom of 

 the sea, to the present time, both they and the surrounding country 

 must have undergone various changes with respect to elevation ; but 

 before making any observations on this subject, I may be allowed to 

 point out the various places where I have seen traces of the chalk 

 formation besides that which I have just describedv In 1838, while 

 making a voyage up the Rio San Francisco, which empties itself into 

 the Atlantic between the 10th and 11th degrees of south latitude, I 

 obtained specimens of the sandstone rock on which the Villa de Penedo 

 is built, and these, on comparison, are identical with those from the 

 upper sandstone of Crato. In 1839, I found the ferruginous sandstone 

 of Crato extending westward from thence about 500 miles ; and in the 

 year 1841, I found, at Maranham, in 2° of south latitude and 44° of 

 west longitude, a formation very similar to that at Crato. The whole 

 island on which the city of Maranham is built consists of a very dark- 

 red ferruginous sandstone. On the mainland, to the west of it, I found 

 the same rock rising a little above the sea level, but placed immedi- 

 ately upon it there is a deposit, more than 50 feet thick in some places, 

 of a yellowish and greenish coloured sandstone, very soft, and in some 

 places of a marly nature. At Maranham, I neither obtained flints 

 nor fossil remains of any kind. 



From these data, then, I think there can be little doubt that the 

 whole of that immense shoulder which forms the most eastern point 

 of the American continent, has at one time been a great depositary 

 for the chalk formation. The only other rocks which I have seen in 

 places which are denuded of those belonging to the chalk are, first, 

 gneiss and mica slate, both abounding in garnets, the layers of 

 which crop out in nearly a vertical direction, as was frequently 

 observed on my journey from the coast, and during my voyage up 

 the Rio San Francisco ; and, secondly, beds of grey coloured primitive 

 clay slate, having the same inclination. The latter, however, I did 

 not observe till within about 18 leagues of the chalk table land. At 

 the termination of these rocks a whitish coarse-grained sandstone 



