166 Geological Observations upon 



it has often been compared to a great canal, which occasionally pre- 

 sents elevated banks, but generally cuts through level pine woods, 

 having clean, gravelly banks, and thus presenting a marked contrast 

 with southern rivers, whose sunken borders, so frequently offer a 

 mere jungle of cane-brake, tall grasses, shrubs and trees. In Bar- 

 tram's travels in North America* we find the following account. of 

 this stream, and his explanation of the unusual transparency of its 

 water. 



" The Indians and traders say that this river has no branches or col- 

 lateral brooks or rivers tributary to it ; but that it is fed or augmented 

 by great springs which break out through the banks. From the ac- 

 counts given by them, and my own observations on the country round 

 about, it seems a probable assertion ; for there was not a creek or riv- 

 ulet to be seen, running on the surface of the ground, from the great 

 Alachua Savanna to this river, a distance of above seventy miles ; yet, 

 perhaps, no part of the earth affords a greater plenty of pure, salu- 

 brious waters. The unparalled transparency of these waters furnishes 

 an argument for such a conjecture, that amounts at least to a proba- 

 bility, were it not confirmed by ocular demonstration ; for in all the 

 flat countries of Carolina and Florida, except this isthmus, the waters 

 of the rivers are, in some degree, turgid, and have a dark hue, owing 

 to the annual firing of the forests and plains; and afterwards the heavy 

 rains washing the light surface of the burnt earth into rivulets, which 

 rivulets running rapidly over the surface of the earth, flow into the 

 rivers, and tinge the waters the color of lye or beer, almost down to 

 the tide near the sea coast. But here behold how different the ap- 

 pearance, and how manifest the cause ! for although the surface of 

 the ground produces the same vegetable substances, the soil the same, 

 and suffers in like manner a general conflagration, and the rains, in 

 impetuous showers, as liberally descend upon the parched surface of 

 the ground ; yet the earth being so hollow and porous, these supera- 

 bundant waters cannot constitute a rivulet or brook, to continue any 

 distance on its surface, before they are arrested in their course and 

 swallowed up : thence descending, they are filtered through the sands 

 and other strata of earth, to the horizontal beds of porous rocks, 

 which, being composed of thin separable laminae, lying generally in 

 obliquely horizontal directions over each other, admi't these waters to 

 pass on by gradual but constant percolation. Thus collecting and as- 

 sociating, they augment and form little rills, brooks, and even subter- 



* Dublin, 1793, p. 223 et seq. 



