THE EOLLERS OR GROUND SEA. 357 



impetuosity. The rise takes place sometimes gradually, but more frequentlj 

 quite unexpectedly, the waves reaching an uncommon height. 

 ' A heavy " Ground Sea " is distinguished by something grand and sublime. 

 The sea approaches in undulating masses, which suddenly rise to large 

 ridg«s, crested with foam, and form billows that burst upon the beach with 

 the greatest impetuosity ; the spray flying, where the waves dash against 

 cliffs, often more than 100 feet high, attended with loud roarings resembling 

 thunder, which subside into a rumbling noise, caused by the nodules and 

 fragments of rock with which the breaker was charged when advancing, 

 which on its retreat roll backward, and are again driven forward by the 

 next surge. Wave then follows upon wave in quick succession, there being, 

 apparently, only a short interval after the third. The sea, for many miles 

 from shore, assumes a peculiar aspect, different tints of blue, from the 

 lightest to the darkest, forming a strong contrast with the snowy foam of 

 the breaking waves, when they strike against a hidden rock, or with the 

 white.line visible along the whole coast. The Eastern Bahamas, the North- 

 Eastern coast of Jamaica and Hayti, but chiefly Porto Rico and the Virgin 

 Islands, and, in a less degree, the Northern Caribbee Islands, are subjected 

 to this Ground Sea. 



It may be considered, as a rule, that whenever the wind gets to the 

 Northward of East for a day or two, there will be a Grotmd Sea on the 

 Northern side of the islands. The friction of the wind on the surface of 

 the water causes little elevations or ridges, which, by continuance of the 

 force, gradually increase, chiefly when the wind sweeps over a great extent 

 of water. Finding no resistance, and having sufficient depth to sink directly 

 down, they proceed with the direction of the wind, and remain natural 

 waves, until they meet repercussion from dashing against the shore, when 

 they rise to an elevation much above their natural state. 



The period when the Ground Sea sets in is generally in October, and it 

 continues, though with some intermission, till April and May. The wind 

 accompanying or preceding a Ground Sea is, generally, from the East of 

 North ; the waves are, therefore, propelled, more or less, in a Western as 

 well as Southern direction, and the Bahamas, and even Bermuda, may 

 escape, whilst the islands from Barbadoes to Porto Rico, but more particu- 

 larly the latter and the Virgin Islands, receive their first impulse. 



A Southern gale will likewise produce a heavy swell on the Southern 

 side of these islands ; and, during the gale of August 30th and 31st, 1833, 

 this was felt with great violence on the Southern shore. But, generally 

 speaking, neither in force nor duration are these surges to be compared 

 with those of the Northern side ; the group of the Virgin Islands being 

 protected, in this direction, by the Caribbee Islands or by the Colombian 

 coasts, and not exposed to the swell of the main ocean. 



To one who crosses during a severe Ground Sea, from the Southern side 

 of Tortola to the Northern, where the breadth of the island is inconsider- 

 able, the singular spectacle is afforded of the sea, which on the Southern 

 side is perhaps "as smooth as glass," on the Northern shore tossing, 

 foaming, and roaring, as if agitated by a severe gale. The effect is most 

 cui'ious, and if it were not for the warning that is heard long before the 

 cause becomes visible, one might fancy the wand of a magician in action. 



