104 A. FE. Verrill—The Bermuda Islands; Geology. 
intense frosts of the Labrador coast, is good proof of their dura- 
bility. A group of these columns is figured by Lyell in his Manual 
of Geology, p. 78, 1853, fig. 97. I saw the same columns in 1861. 
Lyell, in the same work (pp. 74, 75), also describes limestone cliffs 
much eroded by the sea in the Pleistocene period, but now elevated 
180 feet above the sea and situated inland, near Palermo, Sicily. 
They are pitted, encrusted, and infiltrated with stalactitic material 
near the base, like the Bermuda cliffs, and contain holes bored by 
marine bivalves (Lithodomus), the shells of which often still remain 
in the holes, when under the crust. But these cliffs contain sea-worn 
caverns in which are gravel deposits filled with the bones of extinct 
mammals, such as the mammoth, hippopotamus, ete., thus showing 
the great antiquity of the cliffs and caverns. They have evidently 
altered but little in the many thousands of years since the Pleisto- 
cene period, when they were raised from beneath the sea. Lyell 
describes other similar cases in the Morea and other regions, proving 
the remarkable durability of such cliffs. 
Therefore it is not unreasonable to suppose that the date on 
Spanish Rock is genuine, nor to believe that the columns of Tobacco 
Bay, the Cathedral Rocks, etc., have remained much as they now 
are for thousands of years, or since the Champlain period, when 
they were probably elevated above the sea, like those of Niapisca 
Island. 
B. Mechanical action of rain-water. 
Bermuda has a large rainfall. At times the rains are frequent 
and violent. According to Lefroy’s tables, covering eleven and 
sixteen years respectively, the annual rainfall was 54.66 inches at 
Ireland Island, and 48.61 inches at St. George’s. The amount near 
Hamilton during later years has usually varied between 58 and 63 
inches, but in 1898 it was only 48.19; and in 1900 it was 67.05 
inches.* 
The rainfall is usually pretty well distributed throughout the year, 
but is generally greatest in October and November and least in the 
summer months, when droughts are not uncommon, but seldom very 
prolonged. Usually more or less rain falls on from one hundred and 
ninety to two hundred and seven days. During July, 1896, the 
rainfall at the Prospect Observatory was 18.21 inches. On July 
30th the fall was 4.42 inches. 
® See tables, these Trans., xi, pp. 500-502 ; ‘‘ The Bermuda Islands,” pp. 88-90 
455. 
