BRITISH POSTGLACIAL 6- RECENT DEPOSITS. 403 



we know that when the sea-level had fallen to that of the 

 25-30-feet beach, weapons, implements, and ornaments of bronze, 

 had come into use among the natives of Scotland. Probably, 

 also, the climate had become milder, for in none of the most 

 recent raised-beaches (25-30 feet) do we find the slightest indi- 

 cations of a colder temperature than the present. The last 

 elevation of the land or retreat of the sea in Scotland took 

 place long after the knowledge of metals had been introduced. 



My friend Dr. Howden of Montrose has given a very inter- 

 esting description of the postglacial deposits in the neighbour- 

 hood of that town, 1 which agree in all essential points with the 

 similar accumulations in the valleys of the Tay and the Forth. 

 The succession given by Dr. Howden may be briefly summarised 

 as follows — the beds being named in descending order : — 



1. Alluvial Carse-clay and Scrobicularia-stit. 



2. Peat-bed. 



3. Laminated clay with arctic shells. 



The laminated clay belongs to the late glacial series, and 

 has yielded a number of shells and other organisms of arctic 

 types — such as Cyprina islandica, Pecten groenlandicus, Leda 

 arctica, Yoldia pygmcea, etc. The peat-bed is nowhere exposed 

 at the surface, but has been reached in borings and artificial 

 cuttings. At Montrose Gasworks it was found under 20 feet 

 of estuary-mud and sand, the greater part of the section being 

 below the level of the sea. " It rested almost directly upon the 

 glacial marine clay, and contained stems of trees, leaves of bog- 

 plants, and numerous seeds, mostly resembling those of some 

 Juncus" In addition to these Dr. Howden obtained also "a 

 single seed of a cereal, to all appearance the common barley 

 (Hordeum distichum)." The same observer informs us that 

 fragments of peat containing a great many elytra of beetles 

 were found in the sand at a depth of 20 feet below the surface 

 during the construction of a new dock at Montrose. Above the 

 peat-bed at the Gasworks the deposits were of true estuarine 

 character, and contained many estuarine shells. The Carse-clay 

 1 Trans. Geol. Soc. Edin., vol. i. p. 138. 



