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Following Swallow, these may be briefly described in the present connection. Beginning at the top, they are: First Magnesian Limestone. First, or Saccharoidal Sandstone. Second Magnesian Limestone. Second Sandstone. Third Magnesian Limestone. Third Sandstone. Fourth Limestone."
This last is found in pretty large masses, and sometimes mingled with sparry iron-ore, in the ravine of Tocume, to the west of the Silla. Between the spring of Sanchorquiz and the Cross of La Guayra, as well as still higher up, the gneiss contains considerable beds of saccharoidal bluish-grey primitive limestone, coarse-grained, containing mica, and traversed by veins of white calcareous spar.
At the entrance of the Quebrada Seca we remarked great masses of primitive saccharoidal limestone, tolerably fine grained, of a bluish tint, and traversed by veins of calcareous spar of dazzling whiteness. The aspect of the rock is very singular in those places where thin plates of black ampelite alternate with thin, sinuous, and satiny plates of a talcose slate as white as snow.
Other State reports make mention of many caves and fine springs, and also several natural bridges worthy of special notice. In Mr. G.C. Broadhead's report for 1873-1874, he gives a short but interesting chapter on caves and water supplies, in which he says that "Caves occur in the Third Magnesian Limestone, Saccharoidal Sandstone, Trenton, Lithographic, Encrinital and St. Louis Limestone."
Quartz, dense and milky, also in quartz of nearly every colour and appearance, saccharoidal, crystalline, nay, even in clear glass-like six-sided prismatic crystals, and associated with silver, copper, lead, arsenic, iron as sulphide, oxide, carbonate, and tungstate, antimony, bismuth, nickel, zinc, lead, and other metals in one form or another; in slate, quartzite, mica schist, granite, diorite, porphyry, felsite, calcite, dolomite, common carbonate of iron, siliceous sinter from a hot spring, as at Mount Morgan; as alluvial gold in drifts formed of almost all these materials; and once, perhaps the most curious matrix of all, a small piece of apparently alluvial gold, naturally imbedded in a shaly piece of coal.
They are micaceous strata; and thus the true cipollino is a mixture of talcose schist with white saccharoidal marble, and may be said to form a transition link between marble and common stone. It belongs to the Dolomitic group of rocks, which forms so large a part of the romantic scenery of South-Eastern Europe, and yields all over the world some of the best and most ornamental building-stones.
In Europe beds of primitive limestone are generally observed in the mica-slates; but we find also saccharoidal limestone in gneiss of the most ancient formation, in Sweden near Upsala, in Saxony near Burkersdorf, and in the Alps in the road over the Simplon. These situations are analogous to that of Caracas.
And it is an interesting fact that there is a distinct relation between deposits of magnetic iron ore and the metamorphoses of limestones into marbles; so that this substance not only gives to the marbles their colouring, but also their texture. Even the whitest saccharoidal or statuary marble, which it has not coloured, it has created by the crystallisation of the limestone associated with it.
On other spots, instead of silex, carbonate of lime was precipitated, together with more or less of the nucaceous sediment, and gave rise to saccharoidal limestones. At a later period, when the ocean was yet further cooled down, rock-salt and sulphate of lime were locally precipitated in a similar mode.
There seems to be but little doubt, however, that part of the series is equivalent to the Calciferous of other regions. It is also pretty well determined that certain of the lower beds, all below the 'Saccharoidal' Sandstone perhaps, are representatives of the Upper Cambrian or Potsdam. These conclusions appear well grounded both upon stratigraphical and faunal evidence.
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