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The breccia, or agglomerate of the seacoast, which we have just described, has a white tint, and
lies immediately on the calcareous formation of Cumanacoa, which is of a blueish gray. These two rocks
form a contrast no less striking than the molasse (bur-stone) of the Pays de Vaud, with the calcareous
limestone of the Jura *. It must be observed, that, by the contact of the two formations lying upon each
other, the beds of the limestone of Cumanacoa, which I consider as an Alpine limestone, are always
largely mixed with clay and marl. Lying like the mica-slate of Araya north-east and south-west, they are
inclined, near Punta Delgada, under an angle of 60 degrees to the south-east.
We traversed the forest by a narrow path, and went along a rivulet, which rolls foaming over a
bed of rocks. We observed, that the vegetation was every where more brilliant, where the Alpine
limestone is covered by a quartzose sandstone without petrifactions, and very different from the breccia of
the seacoast. The cause of this phenomenon depends probably not so much on the nature of the ground, as
on the greater humidity of the soil. The quartzose sandstone contains thin strata of a
* For example, near Aaraw, Boudry, and Porentrui in Switzerland.