The question sounds rather vague. Nevertheless, I'll try to present some thoughts.
1) In cosmology we use general relativity (GR). GR deals with internal geometry of space-time. Internal geometry is 4-dimensional geometry itself. It is not geometry of some surface in space of higher dimension.
2) The earth surface geometry is external geometry. It is geometry of 2-dimensional surface in 3-dimensional space. E.g. external geometry is able to distinguish a mountain and a ravine. From the point of view of internal geometry a mountain and a ravine are just the same.