William Smith, the father of historical geology, was the first to work out the divisions of the Jurassic, which he did early in the last century. The terms which he employed are local English names, and these, somewhat Latinized in form by the French geologists, are now very generally used as an international scale. These are given in the table. Smith's name for the system, " Oolitic," has been abandoned in favour of the term Jurassic which was first used by Brongniart and Humboldt. It was taken from the Jura Mountains of Switzerland, where the rocks of this system are admirably displayed. In Europe the Jurassic has long been a favourite subject of study, because of the marvellous wealth of beautifully preserved fossils which it contains. For this reason, the Jurassic is known with a fulness of detail, such as has been acquired regarding very few of the other systems; and no less than thirty well-defined subdivisions have been traced through many countries of the Old World. In this country the Jurassic is ill represented and its divisions are not clear.

Jurassic System

England

Oolite

Upper

Purbeck

Portland

Kimmeridge Clay

Middle

Coral Rag

Oxford Clay

Kellaway Rock

Lower

Great Oolite

Inferior Oolite

Lias

General

Portlandian

Upper

Kimmeridgian

Corallian

Oxfordian

Callovian

Bathonian

Middle

Bajocian

Lias

Lower