Two Other Formations, Far Anterior To The Three We Have Just Mentioned, Are The Transition Gypsum (Ubergangsgyps) Of Aigle, And The Primitive Gypsum (Urgyps) Of The Valley Of Canaria, Near Airolo.

I flatter myself that I may render some service to those geologists who prefer the knowledge of positive facts to speculation on the origin of things, by furnishing them with materials from which they may generalize their ideas on the formation of rocks in both hemispheres.

The relative antiquity of the formations is the principal object of a science which is to render us acquainted with the structure of the globe; that is to say, the nature of the strata which constitute the crust of our planet.)

The new salt-works of Araya have five reservoirs, or pits, the largest of which have two thousand three hundred square toises surface. Their mean depth is eight inches. Use is made both of the rain-water, which by filtration collects at the lowest part of the plain, and of the water of the sea, which enters by canals, or martellieres, when the flood-tide is favoured by the winds. The situation of these new salt-works is less advantageous than that of the lagoon. The waters which fall into the latter pass over steeper slopes, washing a greater extent of ground.

The earth already lixiviated is never carried away here, as it is from time to time in the island of Margareta; nor have wells been dug in the muriatiferous clay, with the view of finding strata richer in muriate of soda.

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