TRANSACTIONS OP SECTION E. 683 



elevation, and periods of volcanic activity accompany elevation rather tlian 

 subsidence. 



When a world-shaking earthquake originates on land, dislocations many miles 

 in length have been formed, on the two sides of which large areas have been 

 relatively raised or lowered. In 1891, in Central Japan, a fault was formed 

 having a length exceeding forty miles and a ' throw,' as shown on the surface, 

 of 10 or 20 feet. 



Mr. R. D. Oldham shows that the Assam earthquake of 1897 was probably 

 due to a movement of 10,000 square miles of country along a thrust-plane through 

 a distance of 16 feet. 



The Ontch earthquake of 1819 resulted in a subsidence of 2,000 square miles 

 of country and the elevation of a ridge fifty miles in length. 



When the origins have been suboceanic, soundings have shown that vast 

 depressions have been formed, whilst coast lines have been raised or lowered. In 

 1822 about 100,000 square miles along the coast of Chile were permanently lifted 

 about 3 feet. 



Observations like these indicate that large earthquakes originating in the 

 furrows described are accompanied by a deepening of the same and an elevation 

 of the flanking ridges. This elevation may relieve constraint at volcanic foci with 

 the result that volcanoes, particularly those which have been sealed for many 

 years, may suddenlj' burst into activity, a sequence of events well illustrated by 

 the volcanic historj^ of the Antilles. In these islands there were eruptions in the 

 years 1692, 1718, 1766, 1797, 1802, 1812, 18^6, 1851, and lastly, the most terrible 

 of all, in the present year. All of them seem to have closely followed huge 

 adjustments of the Hay ti- Jamaican fold, or those in the neighbouring folds on the 

 American continent. 



The 10,000 small earthquakes which are recorded in the world every year 

 have not any sensible relationship to volcanic activity. 



Preliminary Note on the Windings of the Evenlode. 

 By Dr. A. J. Herbebtson. 



3. Geograjyhical Plant-groups in the Irish Flora. 

 By R. Lloyd Praeger, B.E. 



Ireland may be roughly likened to a saucer, of which the central depression 

 consists of a plain of Carboniferous limestone, the rim of a discontinuous series of 

 mountain-groups formed of non-calcareous rocks. Much smaller than Great Britain, 

 it displays less diversity of climate as well as of surface, and consequently less 

 diversity of flora. 



The application of W^atson's well-known ' types of distribution ' to Ireland is 

 productive of some interesting results, and shows a considerable diversity of range 

 in the same groups of plants in Great Britain and in Ireland. 



The ' English ' plants of Watson reach in Ireland their maximum on the 

 East coast, in Dublin, Wicklow, and Wexford, and are also remarkably abundant 

 in Clare. Watson's ' Scottish ' plants show a more uniform range in Ireland. They 

 attain their maximum in the northern maritime counties. Thence they spread 

 down the W^est coast in considerable abimdance as far as the Shannon mouth, 

 while on the East coast they decrease rapidly south of Down. Watson's 'High- 

 land ' plants are found chiefly in the west. They attain their maximum on the 

 comparatively low hills of Donegal and West Galway, and are only sparingly 

 represented on the higher mountains in the east, such as those of Down, Wicklow, 

 and Tipperary. Watson's ' Germanic ' group is practically non-existent in 

 Ireland ; the fragments which have reached that country have a quite irregular 

 distribution, with a maximum in Clare. The ' Atlantic ' plants have a more 

 definite distribution in Ireland, ranging round the coast and showing an increase 

 southward. 



