Part 63

Are there any blocks in North America to the north of the Great Lakes?

In Silliman’s American Journal there are many interesting details in regard to the distribution of boulders in the northern parts of North America.

By geest is understood the alluvial matter which is spread over the surface both of the hilly and low country, and appears, according to De Luc, to have been formed the last time the waters of the ocean stood over the surface of the earth.--J.

By marsch, according to De Luc, is understood the new land added to the coasts since the last retiring of the water of the globe from the surface of the earth, and is formed by the sediments of rivers, mixed more or less with sand from the bottom of the sea.--J.

Vol. II. p. 114, 115, 116.

A remarkable fact of this kind is related by Salt, in his second journey to Abyssinia. The Bay of Amphila, in the Red Sea, is formed, he says, of twelve islands, eleven of which are in part composed of alluvial matters, consisting of corallines, madrepores, echinites, and a great variety of shells common in that sea. The height of these islands is sometimes thirty feet above high water. The small island, which differs from the eleven others, is composed of a solid limestone rock, in which veins of calcedony are observed. Does not this small island, we may ask, indicate that some cause has prevented the madrepores from covering it, while they constructed their habitations in the neighbourhood, on bases which probably must be of the same nature as those of the small island?

On glancing over the charts of Kotzebue’s voyage, we are struck at seeing several of these islands grouped in a circular form, connected with one another by reefs which appear to consist of madrepores, and to present, by this arrangement, a small internal sea of great depth, to which an entrance is afforded by one or more openings. May not this arrangement be owing to submarine craters, on the edge of which the lithophytes have erected their habitations?

1824, St. 12. p. 443.

Malté Brun. Precis de la Geogr. Univers. T. ii. p. 459.; Catteau Calleville, Tabl. de la Mer Balt. T. i. p. 158, 188.

See the excellent figures in Blumenbach’s Decades.

Equal to 27,340 yards and 10 inches English measure, or 15½ miles and 60 yards.

In these reductions of the revolutionary French metres to English measure, the metre is assumed as 39.37 English inches.--Transl.

Or 10,936 yards and 4 inches, equal to 6 miles and nearly a quarter, English measure.

Hence the entire advance of the alluvial promontory of the Po appears to have extended to 21 miles 5 furlongs and 216 yards.--Transl.

Equal to 10,936 or 12,030 yards English measure.--Transl.

Or 2,186 yards 2 feet English.--Transl.

Or 20,778 yards 1 foot 10 inches.--Transl.

Or 21,872 yards.--Transl.

Or 18,591 yards.--Transl.

Equal to 9,842 or 10,936 yards.--Transl.

Equal to 6,564 or 7,655 yards.--Transl.

From 19 miles 7 furlongs and 15 yards, to 20 miles 4 furlongs and 9 yards, English measure.--Transl.

Or 15,366 yards.--Transl.

Equal to 9,842 or 10,936 yards.--Transl.

20,231 yards.--Transl.

Exactly 27 yards 1 foot and ¼ of an inch English.--Transl.

Already stated at from 19¾ to 20½ miles; or more precisely, from 34,995 yards 1 foot 8 inches, to 36,089 yards 10 inches English measure.--Transl.

Equal to 76 yards 1 foot 7 inches and 9/10ths.--Transl.