50 . NATURAL HISTORT 



fands, the produce of depofitlons of different dates, and as they are 

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

 fomctimes horizontal, but oftencr inclined, and convex or con- 

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

 pearance of fhells or other marine produdlions, but in a few 

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

 was concreted. They were black as all the fofCl vegetables 

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

 the fand-hllls, grows the moft valuable timber of thefe colonies. 

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

 underwood or vines. The Wallabba, (Parivoa grandifiora of 

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

 the Coumarou or Tonqujebean-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 Hill remain a perfeft flat, 

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

 foil is flill a fliff clay. Hitherto the river is deep all over, ge- 

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

 and tlie fhores on either fide at low water covered with ooze. 

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

 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 diflance from the mouth 

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

 The ncareft to us was a rock of granite projecfting into the 

 ftream, whofe diredlion 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 pofl-holders. It was part of a low 

 ridge of the fame flone which crofled the country, probably to 

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



hills 



