The subject of the recurrence of phenomena in geological time, so prominently brought forward by Prof. Ramsay in his recent address as President of the British Association, is one which cannot fail to be of interest to the geologist, as it constantly presents itself to him in all his inquiries. There are also doubtless many who are prepared to go with Prof. Ramsay to the length of his conclusions, and who believe “that from the Laurentian epoch down to the present day, all the physical events in the history of the earth have varied neither in kind nor in intensity from those which we now have experienced;” whilst others will be inclined to believe that though generally they have resembled one another in kind, yet that some have varied greatly in their intensity.