56 Miss M. K. Andrews on 



The second view of this rhyolite boss includes the moorland 

 behind, and Slemish, the finest example in our district of a 

 volcanic neck, in the extreme distance. 



In connection with the dolerite of which Slemish is 

 composed, I may mention that it was in this rock that my 

 father, Dr. Andrews, by a magneto-chemical process, discovered 

 native iron widely diffused in microscopic particles. The 

 observation was unexpected, as except in meteorites, native 

 iron is of very rare occurrence. Dr. Andrews detected it also 

 in various basalts, in the indurated lias of Portrush, and in a 

 trachyte from Auvergne, but the largest indications were 

 obtained from the olivine dolerite of Slemish. 



The next lantern slides show views of Kenbaan, one of the 

 most striking headlands of our coast. The intrusion of basalt 

 below the chalk anticline is of special interest in connection 

 with the well known controversy between " Neptunists " and 

 " Vulcanists " in regard to the origin of basalt and other 

 igneous rocks. 



My last slide is of Scrabo Hill, which although in Co. 

 Down, is regarded as an outlier of the Antrim Ba&altic Plateau. 

 It affords very fine examples of sills and dykes, exposed in its 

 large quarries of Triassic sandstone. The sandstone has been 

 protected on the top by a capping of dolerite, and the lantern 

 slide shows a typical section with intrussive sills, cut through 

 by a vertical dyke of later age. 



The economic importance of the igneous rocks of Antrim 

 and Down is well kuown, and in regard to this it is sufficient 

 to note the employment of Castlewellan granite in the Albert 

 Memorial, Hyde Park, and to refer to the important inquiries, 

 instituted by Mr. Wilkinson, into the qualities of the various 

 kinds of stones used for building purposes in Ireland. The 

 results of his experiments are given in his work, entitled, 

 " Practical Geology, and Ancient Architecture of Ireland," 

 published in 1845. 



In addition to the ordinary tests, I wish to draw attention to 

 the great value of microscopic sections in determining the 



