44 GEOLOGY. 



From Eeynosa to the Eancho Lomita, 18 miles above the mouth of the river, the surface of 

 the country is of a gently undulating character, which is accounted for in the fact that the col- 

 luvial deposits rest upon underlying cretaceous strata, which become deeper and deeper as the 

 coast is approached. The river is now more serpentine in its course, and at almost every one 

 of its numerous bends may be seen a lagoon, pond, or pool, in which thousands of water-fowl 

 collect and feed. There is little or no tendency in the river to form islands towards its mouth, 

 where it becomes narrower ; its bed, however, is always ixndergoing constant and rapid changes. 

 No bend, under the capricious action of eddies and whirljiools, retains its form for more than a 

 season. 



We noticed at several points, where a new bed had been formed a short time before, that 

 there was scarcely any perceptible difference in the strength of the two channels, the river 

 taking its course through both with equal force and volume. The boatmen not unfrequently 

 found themselves in a sort of " steering dilemma" at such places, not knowing which was the 

 channel. The outlet of the old bed, or its junction with the new, presented quite another 

 aspect, and certainly not inviting entrance to those who come uj). 



It is in this region that the vegetation of the Kio Bravo displays its highest and most lux- 

 uriant develojjment. 



All the bottom-land, not under cultivation and not subject to the action of the water, is 

 covered with dense thickets, almost wholly impenetrable, composed, as they are, of .lofty trees 

 as well as of smaller undergrowth, and of a great variety of creepers and vines, springing up 

 from every spot not otherwise occupied, and filling up all the open and shady spaces, from the 

 foot to the topmost branch of every tree and bush. It is also in the lower portion of this belt 

 (where the Palm tribe is represented by the Chamaerops Palmetto) that the Palmetto attains a 

 growth as gorgeous even as that on the Lower Mississippi ; it extends on the Kio Bravo up to 

 about 80 miles from the Gulf. In addition to the Palmetto common to the lower portions of 

 these two great rivers, the constant appearance of a Tillandsia (Spanish moss) depending from 

 the branches of the trees in long clusters increases the similarity of their scenery. Whilst the 

 existence of this moss proves a higher degree of atmospheric moisture here than in the country 

 above, the occurrence of the Palmetto may indicate the vicinity of the sea. 



There would, perhaps, be no mistake in placing the limits of the maritime belt where the 

 growth of the Palmetto ceases, particularly if we take into consideration the fact that several 

 salt-water loving plants keep company with this rej^resentative of the Palms. The real coast 

 belt, however, in the true sense of the word, may be placed with more propriety in the vicinity 

 of the Eancho Lomita, 18 miles above the mouth of the river, 



THE COAST. 



Lomita, the diminutive of Loma, a long, somewhat flat hill or ridge, forms one of the last 

 topographical monuments on the Rio Bravo. These consist of a low ridge of calcareous clay, 

 bare and almost entirely deprived of any vegetation whatever. The ridge on which the town 

 of Lomita is situated, like several others below, shows marks of being continually under the 

 destructive action of the tide of the sea and flood of the river which meet here. 



From Lomita down the land shows the real character of the seacoast, the vegetation decreasing 

 gradually towards the mouth of the river. Most of the trees here yield the field almost solely 



