82 GEOLOGICAL SPECULATIONS. 



one. It also makes an excellent material for packing 

 glass and earthenware. 



But it is time to take leave of the productions of the 

 sandy shore, and explore those that seek a firmer foot- 

 ing on submarine rocks, the truly prolific soil of the sea. 

 I pass by the intermediate stages of shingly shores, and 

 shores covered with boulders, neither of which are fa- 

 vourable to the growth of marine plants, or the shel- 

 tering of animals. On loose-lying boulders few sea- 

 weeds, except Fucus nodosus, a coarse leathery species, 

 with large air-bladders, and a few unsightly Ulvce, are 

 found ; while the animals are restricted to the Common 

 Limpet, and the least attractive of the Sea Anemones 

 (Actinia Mesembryanthemurti), with scabby patches of 

 Balani and Mussels, a few Periwinkles, &c. By ex- 

 ploring the smaller stones lying on such a shore, many 

 curious Annelides and small Molluscs, small Crabs, &c. 

 may be captured ; and, therefore, these shores should not 

 be neglected by the naturalist : but the labour is often 

 disproportionate to the value of the crop he may ex- 

 pect to reap. The study of such beaches will, however, 

 always interest the geologist, whose speculations take 

 a wider range, and who finds, in the slowly-changing 

 character of such a beach, the explanation of many of 

 the appearances presented to him on land. The gradual 

 formation and accumulation of gravel by the action of 

 water, and the commencement of conglomerate rocks, 

 are often beautifully exhibited. Nor must the debris of 

 marine shells, &c., which marks the limits of ordinary 

 tides, be omitted in the general survey. It is curious 

 to watch the gradual formation of beds of these remains, 



