These volcanic rocks are of undoubted Tertiary origin, say the geologists.  The whole range is for the most part composed of various kinds of trachytic conglomerate.  “From the midst of these vast tufaceous deposits, the tops of the hills, composed of trachyte, a rock which forms all the loftiest eminences, here and there emerge....  The trachyte is ordinarily reddish, greyish, or blackish; it mostly contains mica.  In the southern parts, as near Csik Szereda, the trachyte encloses large masses, sometimes forming even small hillocks, of that variety of which millstones are made, having quartz crystals disseminated through it, and in general indurated by silicious matter in so fine a state of division that the parts are nearly invisible.  The latter substance seems to be the result of a kind of sublimation which took place at the moment of the formation of the trachyte....  Distinct craters are only seen at the southern extremity of the chain.  One of the finest observed by Dr Bone was to the south of Tusnad.  It was of great size and well characterised, surrounded by pretty steep and lofty hills composed of trachyte.  The bottom of the hollow was full of water.  The ground near has a very strong sulphureous odour.  A mile to the SSE. direction from this point there are on the tableland two large and distinct maars like those of the Eifel—­that is to say, old craters, which have been lakes, and are now covered with a thick coat of marsh plants.  The cattle dare not graze upon them for fear of sinking in.  Some miles farther in the same direction is the well-known hill of Budoshegy (or hill of bad smell), a trachytic mountain, near the summit of which is a distinct rent, exhaling very hot sulphureous vapours....  The craters here described have thrown out a vast quantity of pumice, which now forms a deposit of greater or less thickness along the Aluta and the Marosch from Tusnad to Toplitza.  Impressions of plants and some silicious wood are likewise to be found in it."[18]

Since Dr Daubeny’s time there have been many observers over the same ground, the most distinguished being the Hungarian geologist Szabo, professor at the University of Buda-Pest.  A countryman of our own has also taken up the subject of the ancient volcanoes of Hungary, and has recently published a paper on the subject.  Professor Judd has confined his remarks principally to the Schemnitz district in the north of Hungary.  But the following passage refers to the general character of the formation.  Professor Judd says:[19] “The most interesting fact with regard to the constitution of these Hungarian lavas, which in the central parts of their masses are often found to assume a very coarsely crystalline and almost granitic character, while their outer portions present a strikingly scoriaceous or slaggy appearance, remains to be noticed.  It is, that though the predominant felspar in them is always of the basic type, yet they not unfrequently contain free quartz, sometimes