336 Proceedings of the Royal Physical Society. 



and VIII., and Part 1, Vol. IX. — From the Academy. 2. Jahrbuch 

 der Kaiserlich-Koniglichen Geologischen Reichsanstalt, 1865, XV 

 Band. Nro. 3, Juli, August, September. — From the I. R. Geological 

 Institute of Vienna. 3. Natuurkundig Tijdschrift voor Nederlandsch 

 Indie, uitgegeven door de Knoninklijke Natuurkundige vereeniging in 

 Nederlandsch Indie, Deel XXVI., Zesde Serie Deel I., Aflevering 3-6 ; 

 Deel XXVII. , Zesde Serie Deel II. ; Batavia, H. M. Vandorp's Graven- 

 hage; Martinus Nyhoff, 1864. 



The following Communications were read: — 



I. An Inquiry into the Action of the Natural Agencies by which Level 

 Terraces are produced, and into the proofs thereby afforded that the 

 elevation of the central parts of Scotland must have been the effect 

 of a sudden upheaval. By the Rev. James Brodie, Monimail. 



In the central districts of Scotland, both on the east coast 

 and on the west, littoral deposits are found, forming level 

 terraces or beaches, and containing marine shells of existing 

 species. Two terraces have more especially attracted atten- 

 tion. The lower is from 5 to 20 feet above ordinary high- 

 water mark ; the npper is from 15 to 20, or even 25 feet 

 above the lower. The lower terrace varies in breadth from 

 a few yards to several miles ; the npper is generally much 

 more limited in its extent. The accuracy of these state- 

 ments is very generally acknowledged. That these appear- 

 ances indicate the action of water all are ready to allow ; 

 but opinions differ widely as to the nature of that action, 

 and as to the inferences to be drawn from these appearances. 

 The idea generally entertained seems to be that these ter- 

 races were formed beneath the water, that they have been 

 raised to their present position by a slow and gradual process 

 of elevation, and that we must therefore ascribe to the 

 deposits found in them a very great antiquity. In oppo- 

 sition to these views, we are prepared to maintain that the 

 elevation of the central part of Scotland has not been the 

 effect of a gradual rise of the land, but of a sudden upheaval, 

 and consequently that the calculations which rest on the 

 hypothesis of a gradual rise should be set aside. 



Formation of Level Terraces. 



In order to understand the subject aright, we must direct 

 our attention to the manner in which the agency of the 



