The discovery of their true nature was made by Dr William Buckland, who observed that certain convoluted bodies occurring in the Lias of Gloucestershire had the form which would have been produced by their passage in the soft state through the intestines of reptiles or fishes.
Another well-known bed, formerly known as the "Bristol" or "Lias" Bone Bed, exists in the form of several thin layers of micaceous sandstone, with the remains of fish and saurians, which occur in the Rhaetic Black Paper Shales that lie above the Keuper marls in the south-west of England.
To the Lias also can be traced back the Neuroptera, the Trichoptera, the orthorrhaphous Diptera and, according to the determination of certain obscure fossils, also the Hymenoptera (ants).
Diptera of the sub-order Orthorrhapha occur in the Lias and Cyclorrhapha in the Kimmeridgian.
From the evidence of fossils it seems that the higher sub-order - Apocrita - can be traced back to the Lias, so that we believe the Hymenoptera to be more ancient than the Diptera, and far more ancient than the Lepidoptera.
The Lias and Oolite formations are well represented, but the Sequanian and Kimmeridgian subdivisions are absent.
Fragments of wings from the Lias and Oolitic beds have been referred to ants and bees, but the true nature of these remains is doubtful.
Above these, marine Rhaetic beds appear at intervals, notably near Lame, where they are succeeded by Lower Lias shales and limestones.
At Portrush, the Lower Lias is seen on the shore, crowded with ammonites, but silicified and metamorphosed by invading dolerite.
Gulf of Gabes I o g Lemg.W.of Greenwicir 0 Longitude East of Greenwich B 4 D very complete sequence of formations from the Lias to those of recent date.
Rhaetic beds (Infra Lias), consisting of dolomites and siliceous limestones, have been recognized at Saida.
The lower and middle divisions of the Jurassic, composed of massive limestones more or less siliceous and overlain by the marls amd highly fossiliferous limestones of the Upper Lias, play an important part in the constitution of the chief mountains of the Tell.
Fossil Neuroptera occur in the Lias and even in the Trias if the relationships of certain larvae have been correctly surmised.
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.
In the Mesozoic rocks (Trias and Lias) there have been discovered remains of insects intermediate between those ancient forms and our modern cockroaches, the differentiation between forewings and hindwings having begun.
See also Brau de Saint-Pol Lias, fle de Sumatra (Paris, 1884); E.
The most important British ore deposit is the Lower Cleveland bed of oolitic siderite in the Middle Lias, near Middlesborough.
Blende, is also found sporadically in sedimentary rocks; for example, in nodules of clay-ironstone in the Coal Measures, in the cement-doggers of the Lias, and in the casts of fossil shells.
There occur also below the Lias on some parts of the west coast unfossiliferous red sandstones, conglomerates and breccias, presenting lithological resemblance to the Rhaetic group of England.
The Jurassic system - comprising, in descending order, the subdivisions of Upper Oolites (Portlandian Kimmeridge Clay), Middle Oolites (coal limestones; Oxford clay), Lower Oolites (Great Oolite series; Inferior Oolite series), Lias (Upper, Middle, Lower) - is well represented on both sides of the Highlands.
Among these the Lower and Middle Lias can be identified by their fossils.
They comprise a consecutive series of deposits from the bottom of the Lias up to the Oxford Clay.
The Lower, Middle and Upper Lias consist chiefly of shales and shelly limestones, with some sandstones, well seen along the shores of Broadford Bay in Skye and in some of the adjacent islands.
The fossils from the Rhaetic beds belong to the Avicula contorta zone, those from the Lias to the Ammonites angulatus zone, while the blocks of limestone with chert contain Inoceramus, Cretaceous foraminifera and other organisms. The materials yielding these fossils are embedded in a course volcanic agglomerate which gives rise to crags and is pierced by acid and basic igneous ricks.
The jet is a species of petrified wood found towards the bottom of the Upper Lias, and its use for the purpose of ornament dates from very early times.
The Trias is known only at La Ternera near Copiapo, where coal-seams with Rhaetic plants have been found; but the rest of the Mesozoic series, from the Lias to the Upper Cretaceous, appears to be represented without a break .of more than local importance.
From the Permian to the Lias the sequence in the central Himalaya shows no sign of a break, nor has any unconformity been proved between the Liassic beds and the overlying Spiti shales, which contain fossils of Middle and Upper Jurassic age.
The oldest satisfactorily known member of the group is Dimorphodon from the Lower Lias of Dorsetshire.
Equally fine skeletons of Campylognathus have been found in the Upper Lias of Wurttemberg.
Almost continuous plain with the belt of Lias clays, which is the outer border of the Eastern Division; for although a low escarpment marks the line of junction, and seems to influence the direction of the main rivers, there is only one plain so far as regards free movement over its surface and the construction of canals, roads and railways.
South and east of these streams the very similar country is on the Lias clay.
In England, Kimmeridge Clay, Lias clays, London Clay and pulverized shale and slate are all employed for this purpose.
The lias shales of Whitby contain blocks of semi-mineralized wood, or jet, which is black with a resinous lustre, and a fibrous structure.
The commonest impurities are: - (1) organic matter, humus, &c. (exemplified by clay-soils with an admixture of peat, oil shales, carbonaceous shales); (2) fossils (such as plants in the shales of the Lias and Coal Measures, shells in clays of all geological periods and in fresh water marls); (3) carbonate of lime (rarely altogether absent, but abundant.
At the junction between the Trias and Lias are series of beds termed Rhaetics, which seem to mark a transition from one to the other.
The Lower Lias comes next in order, with a valuable bed of ironstone now largely worked.
The Middle Lias, which enters the county near Woolsthorpe, is about 20 or 30 ft.
The Upper Lias enters the county at Stainby, passing by Grantham and Lincoln where it is worked for bricks.
The Lias thus occupies a vale about 8 or 10 m.
The Inferior Oolite, somewhat narrower than the Lias, extends from the boundary with Rutland due north past Lincoln to the vicinity of the Humber; it forms the Cliff of Lincolnshire with a strong escarpment facing westward.
Westward of and above these strata, the Middle and Upper Jurassic formations are found (Lias, Lower Oolite, Oxfordian, &c.), with well-marked and numerous fossils (Ammonites, Nerinaea, Natica, Astarte, Rhynchonella, Echinodermata, &c.); then the Cretaceous rocks, both these and the Jurassic series being largely developed, the Cretaceous fossils including Nautilus, Belemnites, Ostrea, Gryphaea, &c., and some very large Ammonites (Pachydiscus).
_ .i The Jurassic system is represented in Ireland by the Lower Lias alone, aid it is probable that no marine beds higher than the Upper Lias were deposited during this period.