50 NATURAL HISTORT 



fands, the produce of depofitions of difFerent dates, and as tliey are 

 of difFerent materials, thicker in one place, thinner in another, 

 fom^times horizontal, but oftener inclined, and convex or con- 

 cave according to circumflances. We could meet with no ap- 

 pearance of fhells or other marine produ(5lions, but in a few 

 places, pieces of broken vegetables buried in the fand where it 

 was concreted. They were black as all the folhl vegetabkvS 

 that 1 have ever feen in fand-ftone. Upon, and by the fides of 

 the fand-hills, grows the mofl valuable timber of thefe colonies. 

 The trees there are of a good fize, and very clear of obftrudling 

 underwood or vines. The Wallabba, (Parivoa grandiflora of 

 Aublet) j the Sipiri or green-heart, (a new fpecies of laurel) ; 

 the Coumarou or Tonqu^ebean-tree, Coumarouna odorata of 

 Aublet ; the Mora, valuable for boat-timbers, and many others, 

 whofe wood is equally hard and beautiful. 



Continuing to afcend the river, the fand-hills become ra- 

 ther more frequent, but the intervals ftill remain a perfedl flat, 

 though now feveral feet above the level of the ftream, and the 

 foil is ftill a ftiff clay. Hitherto the river is deep all over, ge- 

 nerally from two to five fathoms ; the bottom is mud or clay, 

 aiid the fhores on eitlier fide at low water covered with ooze. 

 About 130 miles up, however, or juft before it begins to fhal- 

 low, the bottom is covered with banks of a hard white or 

 brown fand.. It was a problem for fome time whence all this 

 fand originated in fuch a country. It was foon folved. Lea- 

 ving here the vefTel that had hitherto carried us, we proceeded in 

 a canoe ; and at about 160 or 170 miles diftance from the mouth 

 of the river, we met with the firft proper hills of folid materials. 

 The neareft to us was a rock of granite projecting into the 

 ftream, whofe direcflion it gave a change to at this place, and 

 it ferved for a landing-place to the higheft piece of cleared land 

 upon the river next to the poft-holders. It was part of a low 

 ridge of the fame ftone which crolfed the country, probably to 

 Serbia or beyond it, and was fucceeded by many other feries of 



hills 



