After leaving the Falklands we proceeded to the Rio S.Cruz, following up the river till within twenty miles of the Cordilleras.

Unfortunately want of provisions compelled us to return.
This expedition was most important to me as it was a transverse section of the great Patagonian formation.

I conjecture (an accurate examination of fossils may possibly determine the point) that the main bed is somewhere about the Miocene period (using Mr.Lyell's expression); I judge from what I have seen of the present shells of Patagonia.

This bed contains an ENORMOUS field of lava.

This is of some interest, as being a rude approximation to the age of the volcanic part of the great range of the Andes.