PROCEEDINGS 
OF 
THE GEOLOGICAL SOCIETY OF LONDON. 
Vou. III. Parr II. 1841. No. 78. 
May 5.—John Young, Esq., M.P., Baillieborough Castle, County 
of Cavan; R. H. Cheney, Esq., of Badger Hall, near Shiffnal; 
William Evans, Esq., M.P., Allestree Hall, Derbyshire, and Park 
House, Kensington Gore, London ; and John Houseman, Esq., 
Endsleigh-street, Tavistock-square, were elected Fellows of this So- 
ciety. 
In conformity with Section VI., Clause 8, of the By-Laws, the 
Chairman read, for the first time, the names of the following Fellows 
proposed by the Council to be removed from the Lists of the Society 
on account of arrears of annual contributions :-— 
Thomas Alderson, Esq., John Crawfurd, Esq., Sir George Duckett, 
Bart., John Dunston, Esq., John Hanson, Esq., and James Har- 
field, Esq. 
A Memoir ‘ On the Distribution of the Erratic Boulders, and on 
the contemporaneous unstratified Deposits of South America,” by 
Charles Darwin, Esq., F.R.S., F.G.S., was read. 
The extensive regions more particularly noticed in this paper are 
the plains traversed by the Rio Santa Cruz (lat. 50° S.); Tierra 
del Fuego, including the coasts of the Strait of Magellan, and the 
Island of Chiloe (lat. 43° S., long. 73° W.). 
Patagonia.—Between the Rio Plata and the Rio Santa Cruz, 
Mr. Darwin did not observe any boulders, and the only one he no- 
ticed in ascending the first 100 miles of the latter river was a mass 
7 feet in circumference, about 57 miles from its mouth, or 100 from 
the Cordillera. At 100 miles from the coast, or 67 from the near- 
est slope of the Cordillera, transported blocks first occur, and 12 
miles nearer the chain they are extraordinarily numerous, consisting 
of clay-slate, felspathic rocks, chlorite schist and basaltic lava. 
They are generally angular, and some of them are of immense size, 
one being 60 feet in circumference, and projecting from 5 to 6 feet 
above the surface of the ground. The vast open plain on which 
they lie scattered, is here 1400 feet above the level of the sea, and 
its surface is somewhat irregular, owing partly to denudation and 
partly to the protrusion of hummocks and fields of lava. The plain 
slopes gently and regularly towards the Atlantic, where the sea- 
cliffs are about 800 feet high; but towards the Cordillera it rises 
more abruptly, attaining near the chain an elevation of 3000 feet. 
VOL. Ill. PART II. 2N 
