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.
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).
At Portrush, the Lower Lias is seen on the shore, crowded with ammonites, but silicified and metamorphosed by invading dolerite.
Steep towards the west, where it overlooks the low Lias plain as the Oolitic escarpment, the land falls very gently in slopes of Oxford Clay towards the Cretaceous escarpments on the south and east.
The oldest satisfactorily known member of the group is Dimorphodon from the Lower Lias of Dorsetshire.
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.
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.
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.
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 low escarpments of the harder beds of the Lias are the real, though often scarcely perceptible, boundary between the Triassic plain and the Jurassic belt.