for North America as follows:
| 1. | The impossible areas for petroliferous rocks. | |
| ( a ) | The more extensive areas of igneous rocks and especially those of the ancient shields; exception, the smaller dikes. | |
| ( b ) | All pre-Cambrian strata. | |
| ( c ) | All decidedly folded mountainous tracts older than the Cretaceous; exceptions, domed and block-faulted mountains. | |
| ( d ) | All regionally metamorphosed strata. |