stream now floats the largest ships, and brings to our doors the 

 choicest products of the globe. 



Mr. Robert Chambers, in his interesting and prettily illustrated 

 work on " Ancient Sea Margins," has some judicious observations on 

 the connection of these deposits with those of other parts of Scot- 

 land, especially in the estuaries of the Forth and Tay, pp. 206-208. 



II. TERTIARY PERIOD. 



4. The beds just described overlie towards their margin another 

 series, occupying a peculiar place, and presenting a marked organic 

 sequence, which links on the tertiary age to the existing order of 

 things, and affords another amid the now oft-recurring examples of 

 passages from group to group, which almost defy classification, and 

 show us how past creations shade off into the present, continuously, 

 without a chasm. The deposits in question are well known to geolo- 

 gists as the Clyde Beds, the discovery of which, with an interesting 

 account of their natural history, we owe to Mr. Smith of Jordan- 

 hill. According to his classification, they are as follows, in descend- 

 ing order : 



1. Post-Pleiocene, or Raised Beaches. 



2. Pleistocene, Newer Pleiocene, the Till, or Boulder clay of the glacial 



period. 



3. Sands, gravels, and clays, resting on the Carboniferous formations or 



on the overlying trap rocks. 



Post-Pleiocene, or Raised Beaclies. 



5. When we pass from the river Clyde into the frith at Dum- 

 barton, both shores are seen to be marked by a well defined 

 terrace, 10 to 20 feet above the present tide level, and bounded 

 inland by a steep cliff. The Greenock railway, from the Bishopton 

 tunnel to Greenock, runs along this terrace ; and it is equally 

 well defined upon the Cardross side, from the Leven mouth by 

 Helensburgh to Gareloch-head. The watering places of Gourock, 

 Kempoch, and Ashton, and on the opposite side that of Kilcreggan, 

 stand upon it. In Roseneath peninsula it is extremely well defined 

 and traceable round the whole shore. Everywhere, indeed, upon 

 the shores of the Frith and its islands the same terrace is 

 clearly marked ; nor less so on the west coast, from the Crinan canal, 

 by Oban, up the shores of Loch Linnhe, on Loch Fyne, &c., and 

 along it in most parts of these shores the coast road is carried. The 

 cliff, which bounds it inland at a distance varying from a few yards, 



