52 



ON THE CORALLINE FORMATIONS OF THE OOLITIC 

 ROCKS. 



BY THOMAS WEIGHT, M.D., F.R.S.E., F.G.S. 



la acknowledging the vote of thanks so handsomely proposed by Dr. 

 Bull to Dr. "Wright, for the address he had delivered from Syniond's Yat, on the 

 Geological features of the landscape, Dr. Wright said that there was one subject, 

 upon which, had time permitted, he should have wished to say a few words, 

 when speaking of the Cotteswold Hills and the Oolitic formations in general, 

 and that was in regard to the fact that the Oolitic rocks appeared to have been 

 formed in a coral sea, probably analogous to that which now rolls its waters in 

 the Pacific between 30 degrees of each side of the Equator. 



In the Lower Oolites of England we find a sxiccession of four or more 

 Coral formations, one above another, with great beds of mollusca between them. 

 The Middle Oolite is remarkable for the number and extent of its Coral reefs, 

 and the Upper Oolite for the Coral beds found in the Portland Oolite near 

 Tisbury, in "Wiltshire. In fact, the Oolitic group was accumulated under many 

 changes of condition ; but the idea of a coralline sea in a slowly subsiding 

 area appears to give the nearest approach to that which then prevailed. The 

 Jurassic waters were studded with Coral reefs, extending over an area equal to 

 a great portion of what is now modern Europe. This is proved by the geogra- 

 phical distribution of their Coralline formations. They stretch through England 

 in a diagonal line from Yorkshire to Dorsetsbire ; through France, from the 

 coast of Normandy to the shores of the Mediterranean, forming besides a chain 

 which extends through the central region, from the department of the Ardennes 

 in the north, to Charente Infeiieure in the south, including Savoy, the Hautes- 

 Alpes and Basses-Alpes ; the Jura chain of the Haute-Saone and the Jura 

 Franche-comtc, and the Jura chain of Switzerland in its entire length from 

 Schaffhausen on the Rhine, to Coburg in Saxony, and along the range of the 

 Swabian Alps and the Franconian Jura. Throughout all this widely extended 

 region Jurassic rocks and Coralline strata were accumulating by the living 

 energies of Polypifera through countless ages, as all the different beds of niadre- 

 poric limestone in the Lower, Middle, and Upper Oolites had been formed by 

 the life energies of different species of Anthozoa, and if we might. venture to 

 estimate the lapse of time occupied in the accumulation of the Oolitic Coral 

 beds, by what we know of the duration in time of the life history of some exist- 



