Here and there throughout the mountains of northern Venezuela, the traveller is sure to be struck by the sight of great cliffs and castle-like masses of limestone rock, which add greatly to the effect of the scenery where they occur. From their position it is clear that these were originally parts of a more or less continuous accumulation of lime in a deep, still sea, after more turbulent waters had deposited the Segovia Group. The German traveller Dr. Sievers called this limestone the Capacho Limestone, from Capacho in Táchira. The fossils are similar to those of the period of the higher parts of the chalk. After the deposition of the Capacho Limestone the earth’s crust, which had in this region remained tranquil for a considerable period, again underwent some changes, and in the new shallower sea thus formed sand and mud, with some lime, were alternately laid down. The resulting sandstones, shales, and limestones were named by Dr. Sievers the Cerro de Oro Series, from a hill formed of these rocks in Táchira, and called Cerro de Oro, or Golden Hill, because the very abundant iron pyrites in it were mistaken for the precious metal. Many fossils have been found in the group, and from these it seems that in Venezuela, instead of the break between Cretaceous and Tertiary which we have in England, there was a continuous series of deposits, so that at the base we have chalk fossils, and higher up Eocene forms, the general character of the animal life changing gradually from one to the other. With the consolidation of the Cerro de Oro beds we have a new period of disturbance, in which the mountain chains of northern Venezuela began to be formed as we know them to-day, and the waters of the Orinoco began to flow into the Atlantic more or less by the present mouth of the river. Alongside the newly formed hills, or islands as they would then be, sandstones and shales were deposited to a considerable thickness. They are found outcropping now along the coast and under the Llanos, as well as round the Lake of Maracaibo. The first fossils from them were collected by Mr. G. P. Wall from Cumaná, and it seems fitting to distinguish the whole as the Cumaná Series.