Changes of Level in the Bertniida Islands. — Tarr. 308 
this rock was then elevated and denuded,* and finall}'^ de- 
pressed and attacked by the waves. 
In the last stage it was partly covered by beach deposits of 
pebbles and shells, which were accumulated during a period 
so recent that the fossils contained are the same as those now 
living in the neighboring sea. Then came an uplift, during 
which land shells lived on the beach deposits: but these were 
soon covered by blown sand, and through this action of sand 
accumulation, the outline of the Bermuda hills was perfected 
by the agency of the winds. This, however, was done at an 
elevation which at one ti me was certainly as great as forty or 
fifty feet above the present sea level. 
The last stage has been a depression, causing much land to 
disappear and the outline of the area to become very irregu- 
lar. This has carried the level down nearly to that of the 
beach which was formed before, the uplift occurred, and be- 
fore the dunes were built. There is nothing to indicate that 
these fluctuations of level were ever very great, but everything 
suggests rather slight changes. The fact that beaches are now 
being built, wave cut cliifs rising out of the water, and sea 
caves being excavated, is indication that the land is now 
standing at about the present level with little if any 
change. 
Most of the work of construction of the Bermuda ishinds 
has been done in recent times. I'his certainly applies to the 
dune deposits, which are now consolidated into ro(!k. for they 
rest upon a beach containing shells of now living specimens. 
The base rock, however, is much older, there is a marked un- 
conformity between it and the overlying beds. It was accu- 
mulated and consolidated into dense rock, and then consider- 
ably denuded before the sand dunes began to grow. This 
makes the history of the Bermudas somewhat more complex 
than has usually been supposed, and perhaps carries their his- 
tory back into Pleistocene or even into Tertiary time. 
*It is noteworthy that the peat beds of Ireland island rest on the ir- 
regular surface of the base rock at a level 45 or 50 feet below the sea 
level. This indicates at least the amount of elevation before the sand 
dunes began. 
