ANNIVERSARY ADDRESS OF THE PRESIDENT. H 



are we not necessarily forced to the conclusion that the strata in 

 question represent the true passage-bed from the one formation to 

 the other ? Must we not consider them as pointing out the gradual 

 steps by which Creative power advanced from one formation to an- 

 other ? iVnd, in observing how these and similar strata may, accord- 

 ing to circumstances, be classed either with the Upper Silurian below, 

 or with the Lower Devonian beds above, are we not warned against 

 that partial dogmatism, which sometimes leads us to hasty general- 

 izations founded on local phaenomena, or on evidence derived from a 

 few isolated instances ? 



In this case, however, it is satisfactory to find that one great 

 source of difficulty is removed. There is no question as to the posi- 

 tion of these beds. Found, on the one hand, at the very base of 

 the Old Red Sandstone (if not below it), they constitute the uppermost 

 beds of the Upper Ludlow rocks on the other ; and the only ques- 

 tion which can arise is this : whether, on the strength of palseonto- 

 logical evidence, it is more convenient to class them with the Silurian 

 or Devonian formations, of which they evidently form the connecting 

 link? 



"We are indebted to Mr. Sorby for another communication on a 

 comparatively new and complicated subject ; and it is only due to 

 the author to say that he appears to have worked out his subject 

 zealously and conscientiously. In the last volume of the Edinburgh 

 New Philosophical Journal, he has published a paper " On the Phy- 

 sical Geography of the Old Red Sandstone Sea of the central district 

 of Scotland." Mr. Sorby states that his general conclusions are, that 

 there is a most intimate connexion between the physical geography 

 of a sea and the currents present in it ; and, since their directions 

 and characters can be ascertained from the structures produced in the 

 deposits formed under their influence, that the physical geography 

 of our ancient seas may be inferred within certain limits. He then 

 examines minutely the structure of the Old Red Sandstone rocks, 

 their strata and stratula produced by the action of currents occa- 

 sioned chiefly by the winds, or causes analogous to those which pro- 

 duce the great oceanic currents of the present day, and states the 

 following as the result of his investigations : — " My conclusions are, 

 that in the Old Red Sandstone period there extended across Scotland 

 a branch of the sea, or strait, whose northern shore was somewhere 

 in the line of the mica-schist rocks which extend from Aberdeen to 

 the mouth of the Clyde ; and its southern in the direction of the 

 greywacke rocks that run across from St. Abb's Head to Wigtonshire. 

 In this sea, at the earlier part of the period, there were considerable 

 tidal currents ; but when the upper beds were deposited, they were 

 more or less completely absent, and there were present such as were 

 chiefly due to the action of the wind." 



Mr. Sorby has since extended his investigations to the south, and 

 has recently communicated to us a paper "On the Physical Geography 

 of the Tertiary Estuary of the Isle of "Wight." In this paper the 

 author has endeavoured to show, that from a knowledge of the struc- 

 ture of the sandy and other strata in this locality we may ascertain 



