THE 



JOURNAL OF GEOLOGY 



FEBRUARY-MARCH, 1906 



THE FORMER LAND CONNECTION BETWEEN AFRICA 

 AND SOUTH AMERICA 



ERNEST H. L. SCHWARZ 

 Rhodes University College, Grahamstown, South Africa 



There are two lines of inquiry which lead to a common con- 

 clusion, namely, that in former ages there was a notable land area 

 where now the waters of the Atlantic he. The first is concerned 

 with the evidence afforded by islands in mid-ocean, and the second 

 makes use of the character and conditions of deposition of the rocks 

 on the continents bordering the ocean, and the distribution of ani- 

 mals now living on either side. 



The bulk of the evidence is naturally accumulated in the second 

 line of inquiry, because the continents are more accessible to observa- 

 tion and investigation; but even a httle testimony from oceanic 

 islands is of very great, value, for these are formed by the piling-up 

 of lavas, and the vents penetrate the ocean floor and bring up frag- 

 ments of the solid crust beneath, so that we can actually handle 

 and examine the constituent rocks of the submerged land. 



In setting out the arguments on the first line of inquiry, it is 

 necessary to define what is meant by a continental type of rock. 

 Sir John Murray's hst of continental types is gneiss, schist, sand- 

 stone, and compact hmestone; and generally the term seems to 

 be applied to any rock formed from the detritus of a land-mass, 

 bearing in mind that it is generally accepted that sediments are 

 deposited within two hundred miles of the coast. The inclusion 

 of schists and gneisses seems to imply, in addition, that rocks may 

 be included in the list of continental types which have been sub- 

 Vol. XIV, No. 2 81 



