Last I saw, they used STEP format or dxf format. Solid models always converted into a surface mesh upon export. That said, if you wanted to work in a solid modelling environment alone you would have to pony up about $1500 for a license.

In solid modelling you can create a blended extrusion, which extrudes starting with one polygon and ending with a 2nd polygon, not necessarily with the same number of vertices. The extrusion can be continued along a series of polygons as well forming a complex surface. You can use this complex solid that results as a mould for your strata. In particular, if you are modelling a valley or a deep sea trench, the complex surface would represent the water that fills it.

Then you have to extrude each striation from the side to this complex surface. This process inevitably results in a joining or cutting operation. To retain your complex surface for future use, just create multiple copies of it, one for each striation that you plan to model. Once you cut the layers with your complex surface, each striation can be assigned individual colors, or other material properties. And you can create slices and animations.

Myself I never imported surface meshes. They were always utterly useless, and usually failed to import properly. It is better to import the numerical data, and literally re-create the surface in CAD. If your data is huge, well, consider writing a 3D polyhedron GUI using Visual Basic. I've done it, in fact it's probably the best way to go, but raw code has its difficulties too.