There are numerous and serious obsta cles opposed to the ascertaining of the nature of the substances which compose the great mass or internal structure of mountains, but every thing has been done which art and perseverance will permit. M. Arduini, a gentleman of strong abili ties and indefatigable research, exerted every means in his power some years past to obtain a knowledge of the interior state of the Vicentine and Veronese hills, which he'divides into mantes prima•ros, se. cundarios, and tertiarios.
The monteR privnetriot is a vast body of slate, extending under the calcareous bills, which he concludes existed prior to their origin.
The monies secundatioe are large calca reous hills formed into strata, composed of a close impalpable limestone, and in terspersed with marine petrifactions, similar to parts of the Alps, and the chain of mountains which separate Germany from Italy.
Mantes tertiaries, are the lower bills, consisting of small beds of limestone, abounding with petrifactions, and with casual interventions of sand and clay, but are of a later origin, since incumbent on the " montes secundarios," and produced by their decay, variously washed down and accumulated together.
The slate of the first division is argilla ceous, containing micaceous particles of the colour of silver, is crossed by veins of quartz, larnellated, and often appears in waved strata. It extends to the greatest depth of any rock in the neighbourhood, and has never been cut through, from which circumstance it cannot be decided whether granite Wends beneath it, as is usual in other mountainous countries, "though this be very probable," says Fer ber, "since the granite rocks appear from under ground in the higher Tyrol, and the grey granite, or granitello, is to be found near Tozzino and Primiero, at the spring of the river Cismonoe, which fhlls into Brenta.
The calcareous Alps consist of strata of a close impalpable grain, with little mix ture of saline matter and petrifactions. The deepest stratum of limestone from the base to the middle of the hill is com posed of numerous small masses, and the exterior being subject to the action of rain-water, it is formed into chasms, leav ing the intervals in elevations of a dark lead-colour; the petrifactions scattered through it arc small bivalves and rifled tellines. The next stratum is inconsider able, but a better white, more solid, and servesfor architectural purposes; the up per part contains no petrifactions, the lower has some unknown ostracites. The third stratum is in many small beds, in some instances furnishing sea-shells, and in others destitute of petrifactions. The part connected with the fourth stratum consists of oolithes. The fourth stratum is composed of several smaller, which are either red, containing ammonites, of very considerable size, or completely white, with petrifactions or ammonites. The
red Veronese marble, abounding with ammonites, is procured from this stra. turn. The fifth division consists of an in finite variety of beds of white limestone, those in the highest mountains, particu larly Monte 'l'orraro, contain no marine productions, but the rest abound with va rious, each stratum being filled with a pe culiar species. The surfaces of these Alps on the summits is called scaglia, by the Italians, and consists of a calcareous bed, in some parts containing nodules, and in others, less extensive, numerous flints of various colours. Covering the mountains, it declines under the Montes Tcrtiarios Bericos, and ascends on the opposite side to the volcanic hills, by the sides of which it appears to have been raised, and then broken. The scaglia is destroyed in many different places by the weather, and is only to be found in a per fect state in the valleys and cavities. M. Arduini discovered red flints, branching like coral, in the scaglia of Monte di S. Pancrazio, and that spread on the volca nic hills near Padua is perforated by sul phurous hot wells.
The several strata of the hills or moun tains in question have been originally dis posed in an horizontal direction, but those are deranged, and broken into large fis sures by the force of volcanic eruptions and earthquakes, through which lavas were ejected, consequently they are sunk in sonic places, in others wholly reversed, and sometimes they are found oblique, and even vertical. Inundations, and the obstructions of the course of rivers, caus ed by the above means, have also operat ed to produce many changes, which are particularly conspicuous at Ayorth, in Valle Imperina. The fields near Gallic), Asiago, Campo di Rivere, &c. situated on the mountains far above the level of the sea, arc strewed with vast numbers of se parate fragments of granite, quartz, and other vein-rocks, which appear to have been detached by violence from the pri mitive mountains of Tyrol. Similar pieces are found on the same horizontal elevation in Feltrino, separated by the Brenta from the others, and westward on the same heights from Astico to the river Adige. Their number and variety of bulk is re markable at Tonezza, and near Folgaria, where the hills being entirely calcareous, entirely destitute of sound and primitive strata, demonstrate that the fragments al hided to are foreign to the places in which they are deposited. As no possible move ment of water could, in the nature of things, be supposed to elevate these masses, it is equally fair to suppose, that streams gushing down the mountains have carried them to their present situa tions, from those vast ruptures observable in every direction on mountains, doubt lessly caused, in the first instance, by earthquakes, filling the usual channels of great bodies of water.