Answer:
Sub-surface rights
Explanation:
Sub-surface rights refers to the right to obtain all resources ( such as oil, minerals, or gas ) that located underground / beneath our private property.
In the excerpt above, we know that the deposit of the shale is located underneath the farmstead owned by the his family. According to sub-surface right , This Abe could make a strong legal case that his family should be the one that held the full right to obtain and mange that resource.