CHAPTER XVI 

 OLDER MORAINES AND ERRATICS 



Descriptions have already been given (Chapter V., pp. 94-98) of the old moraines 

 of the East Fork of the Fei'rar Glacier, of Dry Valley, and of the Stranded Moraines, 

 Avhile in the same chapter (pp. 110-113) descriptions are given of the principal 

 moraines on Ross Island. 



Perhaps the most interesting of these old moraines are those of Ross Island, 

 chiefly relics of the moraines formed by the Ross Barrier at a time when, at its 

 maximum, it completely enveloped Ross Island, converting it into a gigantic nmiatak. 

 The barrier ice rose to a height of at least 1000 feet above sea-level on the flanks 

 of Erebus, and to about 800 feet above sea-level on the eastern slopes of Mount 

 Terror. A general view of these moraines is shown in the view of Erebus forming 

 the Frontispiece to this Memoir. It will be seen from this photograph that the 

 moraines have the appearance of a huge hummocky terrace, rising to a height of 

 a little over 1000 feet (305 metres) above sea-level. Between the hummocks are 

 numerous desiccated tarn or lake basins containing thin deposits of algal peat with 

 dried lake muds enclosing diatomaceous remains. These moraines are of two kinds : 

 ( 1 ) Moraines left by the old Ice Barrier. These are characterised near Cape Royds 

 by the presence of numerous erratics of granite, quartzite, &c., wholly foreign to Ross 

 Island. (2) Ancient moraines of the glaciers of Mount Erebus, and composed of 

 fragments of the local lavas and tufts of Ross Island intermixed with a little re- 

 distributed morauie of type 1. What are probably upthrust portions of the marine 

 sediments of McMurdo Sound were discovered by us at about 160 feet (49 metres) 

 above sea-level above Backdoor Bay, near the extreme left of the Frontispiece, and 

 also near Cape Barne, towards the right of the picture. These are described in 

 detail in Chapter XVII. 



The general appearance of the glaciated area in the vicinity of Cape Royds is 

 shown on Plate LXXXIV. The bulk of the morainic material is in the form of a 

 firmly compacted rubble and gravel. The fragments, mostly of Ross Island lavas, 

 are from 1 to 2 inches in diameter, with a good deal of finer material between, chiefly 

 powdered or splintered felspars. 



These rubbly rock fragments are mostly angular and sub-angular, and while they 

 show evidence of having been bruised a good deal, seldom exhibit striae. The 

 general appearance of the moraine rubble left by the old Ptoss Barrier when it filled 

 McMurdo Sound is shown on Plate LXXXV. Fig. 2. 



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