I don't think the issue is "shallow soils".  I think the issue is the kind of soils that you have.  I can show you soils that are just as shallow as what you have - if not more so.  And I don't think we have the same concerns that you have.  The difference is the water infiltration rate and water percolation rate of these soils.  I am thinking of Berks and Weikert shale soils.  You can look them up in a PA Soils Survey if you wish. 
I would guess that the issue you have is that the water does not have anywhere to go down thru the soil profile, so once that soil profile gets full, then the top surface is more susceptible to erosion.

Someone mentioned Steve Groff.  I am almost certain that Steve Groff does not have the same kind of soils that you have, and so I don't think it would be valid to compare what is happening on Steve's farm to what you are seeing in Adams Co.

My 2 cents.