/ White or greyish limestone, often in beds
| three or four feet thick.  Total thickness
| of the formation above 2000 feet.  Upper
| part fossiliferous, with some strata
2.  Dachstein beds.      <  composed of corals (Lithodendron.)
| Lower portion without fossils.  Among the
| characteristic shells are Hemicardium
| Wulfeni, Megalodon triqueler, and
\ other large bivalves.

/ Red, pink, or white marbles, from 800 to
| 1000 feet in thickness, containing more
| than 800 species of marine fossils, for
3.  Hallstadt beds        | the most part mollusca.  Many species  of
(or St Cassian).   <  Orthoceras.  True Ammonites,
| besides Ceratites and
| Goniatites, Belemnites (rare),
| Porcellia, Pleurotomania, Trochus,
\ Monotis salinaria, &c.

                         / A. Black and grey \ Among the fossils
4.  A. Guttenstein beds. | limestone 150 feet | are Ceratites
   B. Werfen beds, base | thick, alternating | cassianus,
      of Upper Trias? | with the underlying | Myacites
      Lower Trias of < Werfen beds. > fassaensis,
      some geologists. | B. Red and green | Naticella
                         | shale and sandstone, | costata, &c.
                         \ with salt and gypsum./

In the United States, rocks of Triassic age occur in several areas between the Appalachians and the Atlantic seaboard; but they show no such triple division as in Germany, and their exact place in the system is uncertain.  The rocks of these areas consist of red sandstones, sometimes shaly or conglomeratic, occasionally with beds of impure limestone.  Other more extensive areas where Triassic rocks appear at the surface, are found west of the Mississippi, on the slopes of the Rocky Mountains, where the beds consist of sandstones and gypsiferous marls.  The American Trias is chiefly remarkable for having yielded the remains of a small Marsupial (Dromatherium), and numerous footprints, which have generally been referred to Birds (Brontozoum), along with the tracks of undoubted Reptiles (Otozoum, Anisopus, &c.)

The subjoined section (fig. 139) expresses, in a diagrammatic manner, the general sequence of the Triassic rocks when fully developed, as, for example, in the Bavarian Alps:—­

[Illustration:  Fig. 139.  GENERALIZED SECTION OF THE TRIASSIC ROCKS OF CENTRAL EUROPE.]

With regard to the life of the Triassic period, we have to notice a difference as concerns the different members of the group similar to that which has been already mentioned in connection with the Permian formation.  The arenaceous deposits of the series, namely, resemble those of the Permian, not only in being commonly red or variegated in their colour, but also in their conspicuous paucity of organic remains.  They for the most