Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/410

 by far the most compact of the red strata I met with in the island. I saw this red lava also in the Island of Teneriffe, to the eastward of Santa Cruz, as well as in the neighbourhood of Orotava.

I have thus endeavoured to give you a slight sketch of that which appeared to me most deserving of attention in the Island of Madeira. The short stay I was able to make there prevented a more accurate survey of the island; yet I saw enough to induce me to recommend a careful examination of the strata to those who may have more time than I had to spare, and more knowledge to estimate the value of that which was to be seen. To my mind, the most interesting geological facts are, 1st. The intersection of the lava by dykes at right angles with the strata. 2dly, The rapid dips the strata make, particularly the overlaying of that of the Brasen Head, to the eastward of Funchal, where the blue, grey, and red lavas are rolled up in one mass, and lie in a position as if they had all slipped together from an upper stratum. 3dly, The columnar form of the lava itself reposing on, and being covered by, beds of scoriæ, ashes, and pumice, which affords a strong argument for the volcanic origin of the columns themselves; and 4thly, The veins of carbonate of lime and zeolite, which are not found here in solitary pieces as in the vicinity of Ætna and Vesuvius, but are amid the lavas and in the strata of pumice and tufa, and are diffused on the lava itself, and occasionally crystallized in its cavities.