The sedimentary deposits include slate, limestone and sandstone.
The sedimentary rocks are affected by many dikes and sheets of igneous rock, some of the latter being extrusive and some intrusive.
Such changes seem, however, to have been very rapidly accomplished, as pebbles of completely formed coal are commonly found in the sandstones and coarser sedimentary strata alternating with the coal seams in many coalfields.
On the whole, the Proterozoic rocks are predominantly sedimentary and subordinately igneous.
Deposits of brown iron ore of great economic value occur in many sedimentary rocks, such as the Lias, Oolites and Lower Greensand of various parts of England.
Immense -sheets of dolerite, gabbro, or allied basic rocks indicate eruptive materials intruded as sills or poured out as lavas contemporaneously with the sedimentary formations among which they lie.
The prevailing formations appear to be granites which are veined with white quartz, and underlie old sedimentary brown sandstone and limestone formations.
Outside the lower end of each large transverse glen there is a scree of sedimentary matter.
The meta-sedimentary rocks of the Archean include metamorphosed limestone, and schists which carry carbonaceous matter in the form of graphite.
Metamorphosed sedimentary rocks are widely distributed in the schistose series, but they are distinctly subordinate to the meta-ignecius rocks, and they are so highly metamorphic that stratigraphic methods are not usually applicable to them.
The ore is chiefly haematite, and has been developeci from antecedent ferruginous sedimentary deposits, through concentration and purification by ground water.
Guye formation (sedimentary beds with some lava flows) 3500 ~ ft.
The Keewatin and Huronian, consisting of greenstones, schists and more or less metamorphosed sedimentary rocks, are of special interest for their ore deposits, which include most of the important metals, particularly iron, nickel, copper and silver.
The several ranges of the Cordillera show very different types of structure and were formed at different ages, the Selkirks with their core of pre-Cambrian granite, gneiss and schists coming first, then the Coast Ranges, which seem to have been elevated in Cretaceous times, formed mainly by a great upwelling of granite and diorite as batholiths along the margin of the continent and sedimentary rocks lying as remnants on their flanks; and finally the Rocky Mountains in the Laramie or early Eocene, after the close of the Cretaceous.
This latest and also highest range was formed by tremendous thrusts from the Pacific side, crumpling and folding the ancient sedimentary rocks, which run from the Cambrian to the Cretaceous, and faulting them along overturned folds.
The Great Valley Region consists of folded sedimentary rocks, extensive erosion having removed the soft layers to form valleys, leaving the hard layers as ridges, both layers running in a N.E.-S.W.
Timor consists of a core of ancient rocks (Archean?) upon which rest Permian and later deposits of sedimentary origin.
The mountain range that runs out towards the north-east of Sicily is composed of crystalline rocks precisely similar to those forming the parallel range of Aspromonte in Calabria, but both of these are girt about by sedimentary strata belonging in part to an early Tertiary epoch.
The core is formed by the mountain masses of Rhodope, Belasitza, Perin and Rila; and here Palaeozoic and Mesozoic beds are absent, and the earliest sedimentary deposits belong to the Tertiary period and lie flat upon the crystalline rocks.
In general, however, the central area is one of faulting rather than of folding, and the sedimentary beds sometimes lie in troughs formed by faults.
The lowest of these younger rocks are the various sedimentary and volcanic members of the Old Red Sandstone.
Determined by the inequalities of surface of the overlying mantle of sedimentary material, they would be wholly independent of the geological structure of the rocks lying.
The central, southern and eastern Highlands are occupied by metamorphosed sedimentary and igneous rocks, to which has been provisionally assigned the name of Dalradian, from the old Celtic kingdom of Dalriada.
Where a thick group of coarse hard grits intercalated in the sedimentary rocks crops out it rises into a chain of lofty rugged hills, of which Ben Ledi and Ben Vorlich are examples.
The Eastern Cordillera is composed of gneiss, mica and chlorite schist and other crystalline rocks of ancient date; the Western Cordillera, on the other hand, is formed of porphyritic eruptive rocks of Mesozoic age, together with sedimentary deposits containing Cretaceous fossils.
They constitute, in fact, an incomplete rim around the basin of sedimentary beds which occupies the Amazonian depression.
It consists of a series of plateaus formed of sedimentary rocks which mainly belong to three formations of widely separated ages, and which rest on a platform of granitic and metamorphic rocks.
The oldest rocks consist of granite and schist, penetrated by intrusive dykes, and upon this foundation rest the flat-lying sedimentary deposits, beginning with a sandstone like the Nubian sandstone of Egypt.
The phosphatic rocks which occur among the sedimentary strata are the principal sources of phosphates for commerce and agriculture.
These terminal lakes, or more accurately sedimentary plains, are therefore almost always dry."
There are ancient rocks, however, in New Caledonia, which .has a geological affinity with New Zealand; old sedimentary rocks are known in New Pomerania, besides granite and porphyry, and slates, sandstone and chalk occur in Fiji, as well as young volcanic rocks.