608 REPORT— 1881. 



and numerous extinct craters, afford testimony so plain, that he who runs may 

 read their history. The time when they became extinct would doubtless amaze 

 us by its magnitude, if it could be stated in years, but yet it is comparatively so 

 recent that not all the undying forces of atmospheric degradation have been able 

 to obliterate their individual origin. 



It is, however, generally very different with respect to volcanoes of Mesozoic 

 age, for though Lyell stated with doubt, that volcanic products of Jur.assic date 

 are found in the Morea, and in the Apennines ; and Medlicott and Blanford con- 

 sider that probably the igneous rocks of Rajmahal may be of that age, we must, per- 

 haps, wait for further information before the question may be considered as finally 

 settled. Of Jurassic age no actual craters remain. Darwin also has stated, on 

 good grounds, that in the Andes a line of volcanic eruptions has been at work from 

 before the deposition of the Cretaceo-oolitic formation down to the present day. 



In the British Islands we have a remarkable series of true volcanic rocks, the 

 chronology of which has been definitely determined. The oldest of these belong 

 to the Lower Silurian epoch, as shown, for example, on a large scale in Pembroke- 

 shire, at Builth in Radnorshire, in the Longmynd country west of the Stiper 

 stones in Shropshire, and on a far greater scale in North Wales and Cumbria. Of 

 later date we find volcanic lavas and ashes in the Devonian rocks of Devon, and 

 in the Old Red Sandstone of Scotland. The third series is plentiful among the 

 Carboniferous rocks of Scotland, and in a smaller way associated with the 

 Coal-measures of South Staffordshire, Warwickshire and the Clee Hills. The 

 fourth series chronologically is associated with the Permian strata in Scotland, and 

 the fifth and last consists of the Miocene basaltic rocks of the Inner Hebrides and 

 the mainland of the AVest of Scotland. 



In the liritish Islands the art of geological surveying has, I believe, been 

 carried out in a more detailed manner than in any other country in Europe, a 

 matter which has been rendered comparatively easy by the excellence of the 

 Ordnance Survey maps both on the 1-inch and the 6-inch scales. When the 

 whole country has been mapped geologically little will remain to be done in geo- 

 logical surveying, excepting corrections here and there, especially in the earliest 

 published maps of the South-west of England. Palfeontological detail may, how- 

 ever, be carried on to any extent, and much remains to be done in microscopic 

 petrology which now deservedly occupies the attention of many skilled observers. 



Time will not permit me to do more than advert to the excellent and well- 

 known geological surveys now in action in India, Canada, the United States, Aus- 

 tralia, New Zealand, and South Africa. 



On the Continent of Europe there are National Geological Survej's of great 

 and well-deserved repute conducted by men of the highest eminence in geological 

 science, and it is to be hoped the day may come when a more detailed survey will 

 follow the admirable map executed by Sir Roderick Murchison, De Verneuil, and 

 Count Keyserling, and published in their joint work, 'The Geology of Russia in 

 Europe and the Ural Mountains.' 



It is difficult to deal with the Future of Geology. Probably in many of the 

 European formations, more may be done in tracing the details of subformations. 

 The same may be said of much of North America, and for a long series of years 

 a great deal must remain almost untouched in Asia, Africa, South America, and 

 in the islands of the Pacific Ocean. If, in the far future, the day should come 

 when such work shall be undertaken, the process of doing so must necessarily be 

 slow, partly for want of proper maps, and possibly in some regions partly for the 

 want of trained geologists. Palaeontologists must always have ample work in the 

 discovery and description of new fossils, marine, freshwater, and truly terrestrial ; 

 and besides common stratigraphical geology, geologists have still an ample 

 field before them in working out many of those physical problems which form 

 the true basis of Physical Geography in every region of the earth. Of the 

 history of the earth there is a long past, the early chapters of which seem to be 

 lost for ever, and we know little of the future except that it appears that ' the 

 stir of this dim spot which men call earth,' as far as Geology is concerned, shows 

 ' no sign of an end.' 



