Mr. Gardner on the Existence of Chalk in BrazU. 161 



makes its appearance, and is probably equivalent to the ferruginous 

 sandstone found on the west side of the range. From this, it would 

 appear, that between the cretaceous series and the primary stratified 

 rocks, there are no traces either of the carboniferous or the oolitic 

 formations, nor in any part of Brazil through which I passed, did I 

 meet with any signs of them.* 



The country from the coast to the chalk district is very level, and 

 large tracts of it all the way up consist of what are called Vargems by 

 the Brazilians. These are large open spaces destitute of trees or 

 shrubs for th« most part, and only covered with herbaceous vegetation, 

 and that sparingly, during the season of the rains. They are either 

 covered with a kind of coarse white sand, or gravel of various sizes, 

 which gives them the appearance of the dried up bed of an immense 

 river. Much of this gravel consists of flints. Intermingled with these 

 are numerous boulders of various sizes, some of the largest being four 

 feet in diameter. They are all more or less rounded, and consist of 

 granite, gneiss, and quartz. Wherever these gravelly tracts do not 

 exist, the surface of the country is covered with a deposit of the same 

 kind of red clay which lies over the upper sandstone of the table land. 

 To the west of the table land large tracts are covered with the vari- 

 ously shaped ironstone nodules which are found in the ferruginous 

 sandstone, and which have accumulated from the decay of that rock.t 



I have now to offer a few remarks on the changes of elevation which 

 this part of the continent has undergone since the chalk rocks were 

 first deposited. That this deposition took place at the bottom of a 

 shallow ocean there can be no doubt. That at some subsequent period 

 it has been gradually elevated above the level of the sea also admits of 

 no doubt. That this elevation has been gradual is evident from the 

 horizontal position of the strata of which the deposit is formed ; for 

 had the elevating cause been sudden and violent, the original position 

 of them would not have been so perfectly maintained. The long 

 elevated table-land was probably the first part which emerged from 

 the sea, and for a long period subsequently must have formed a neck 

 of land separating the Atlantic Ocean on the east from the great bay, 

 which the immense valley to the westward must then have formed. 



* My friend, Dr. J. Porigot, has, however, found coal abundantly in the island of 

 Santa Catherina, in the south of Brazil. He was employed, about three years ago, to 

 explore that country for coal, and, in a pamphlet which he published, in 1841, entitled 

 *^Memoria Sobre a$ Minos de CarvaS de Pedra do Brazti" he mentions a bed, about three 

 feet thick, of considerable extent. The coal which Spix and. Martins inform us exists 

 near Bahia, Dr. Parigot found to be beds of lignite ; and the probability b that they are 

 equivalent to that which I found at Crato. 



t Sandy nodules with a chalky aspect from this formation were found by Dr. R. D. 

 Thomson to consist of, — 



Silica, 7608 



Alumina, 17-32 



Water, 628 



99-6« 



