400 Geological Society. 



have contained have decomposed and disappeared. In regard to 

 the great numbers of these shells preserved throughout the bed at 

 Gore CHfF, and in many other places even at greater depths, it will 

 not seem surprising to those who have observed the number of dead 

 land shells vvhich are strewed over the surface of the chalk downs, 

 or lie concealed in the green turf in numbers almost as countless as 

 the blades of grass. If the slightest wash of water should pass 

 over such a soil, it must float off myriads of these shells, and they 

 would immediately be involved in that white cream-coloured mud 

 which descends from wasting hills of chalk after heavy rains. Land 

 shells so buried may retain their colour for indefinite periods, as is 

 shown by the state of species in the loess of the Rhine, and even in 

 tertiary strata of much higher antiquity. 



While a variety of geological monuments are annually discovered 

 which attest modern alterations in the level of the land, it is im- 

 portant to remark that new testimony is also daily obtained of the 

 rising and sinking of land in our own times. I discussed at some 

 length, in my last Anniversary Address, the evidence for and against 

 the upheaval of the coast of Chili during the earthquake of 1822, a 

 controverted point to which our attention has lately been again re- 

 called. I may remark, however, that since we have ascertained the 

 fact of a rise of three, five, and even ten feet in parts of the same 

 country in 1835, so distinctly attested by Captain Fitzroy, all 

 doubts entertained as to the permanent effects of a preceding con- 

 vulsion are comparatively of small interest. Don Mariano Rivero 

 dissents from the opinion that a change of level occurred at Valpa- 

 raiso in 1822, and Colonel Walpole, after seeing the ground and 

 conversing with persons who were on the spot in 1822, and who 

 still reside there, also considers the statement of a rise to have been 

 inaccurate. On the other hand Mr. Caldcleugh, who was formerly 

 sceptical on the same point, has now come round to the opinion of 

 Mrs. Callcott (Maria Graham), and believes that an elevation of 

 land did take place. 



Mr. Darwin, whose opportunities of investigation both in Chili 

 and other parts of South America have been so extensive, thinks 

 it quite certain that the land was upheaved two or three feet 

 during the earthquake of 1822, and he met with none of the inha- 

 bitants who doubted the change of level. He states that the rise 

 of land, even in the bay of Valparaiso, was far from being uniform, 

 for a part of a fort not formerly visible from a certain spot has, 

 subsequently to the earthquake, fallen within the line of vision. 

 The most unequivocal proof of a recent rise is drawn from the 

 acorn-shells, Balanidce, found adhering to the rock above the reach 

 of the highest tides. These were observed by Mr. Darwin sixty 

 miles south of Valparaiso, and at Quintero, a few miles to the north 

 of it; but his friend Mr. Alison detected them on a projecting point 

 of rock at Valparaiso itself. The attached shells were there seen 

 at the height of fourteen feet above high-water mark, and were only 

 exposed upon the removal of the dung of birds, by which they would 

 have been concealed from ordinary observation. In Mr. Darwin's 



