136 The Geology of the Cluden Basin. 



field to the north-west of Xewbridge farmhouse, where a narrow- 

 sand-pit has been dug. 



These long ridges, either isolated or parallel, which overlie 

 and obscure the ancient beaches, are now known as eskers. 

 They are associated in the Irish and Scotch folk-lore with the 

 brownies and fairies of the superstitious past. Their peculiar 

 shape and frequent isolation were a standing myster)^ to our fore- 

 fathers, and were promptly relegated to the super-natural. To 

 that romance born of ignorance is now added the greater romance 

 of scientific knowledge. Small streams on the surface of the 

 glacier fell into a large crevasse, forming a torrent at or near 

 the bottom of the ice. Immense quantities of debris transported 

 by glacial erosion were swept into these streams and deposited 

 by torrential water. Their formation was accomplipshed in a 

 convex manner until the arch reached the ice roof of the tunnel, 

 whereupon the stream was diverted into other channels parallel 

 with the first. At Fourmerkland, Cluden Mill, Hardlawbank 

 Ford, and Lincluden Mains, where sections can be seen, the 

 internal arrangement always corresponds with the external shape 

 of the esker. 



During the formation of the highest marine terrace the 

 Cluden would enter the sea between Roughtree and Woodhouses 

 in the form of an extended ice-sheet ; but aftr the sea had re- 

 treated to the lower terrace the Cluden glacier would salve its 

 icebergs with a loud splash near the site of the \-illage. As the 

 ice finallv retreated up stream it would throw down its surface 

 rubbish in the nature of terminal moraines, and effectually block 

 the torrential stream in the neighbourhood of Nether Gribton. 

 The water thus dammed back by morainic agency accumulated 

 until a lake was formed reaching up towards the Canal Wood. 

 Ultimatelv the pressure of the water burst the barrier at its 

 weakest point, and ran swiftly between the parallel ridges at the 

 100 feet level until Woodlands and Cluden Bank were reached, 

 where it descended abruptly in the form of a waterfall or cascade. 

 Since then the stream has been steadily digging out for itself a 

 deeper and a quieter channel. As a result of this river erosion 

 the falls have receded up stream fully half-a-mile, leaving 

 precipitous walls of sandstone and breccia. At this point the 

 gorge abounds with geological problems pressing for solution; 

 but the dominating ideas are the remoteness of the Ice Age and 



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