The principle of the magnetic vector method is briefly explained.

The salient geological features of Kentucky are investigated as to their regional magnetic effects. It is found that the Western and Eastern geosynclines show up magnetically as negative anomalies, but that also the Cumberland River arch and the Lexington dome show up as negative anomalies. From this follows that some of the outcropping beds in Kentucky are of a higher magnetic permeability than the underlying beds and Basement complex.

The study of the magnetic vector map in Michigan reveals a number of magnetic high trends, which are shown to correspond to known structural trends, such as the Howell-Owosso anticline and the Muskegon anticline. The deepest area of the Michigan basin is indicated by a negative magnetic anomaly.

Practical value and application of the magnetic vector maps to field problems is explained by the example of the newly discovered Hart field. Apart from the valuable information obtained by magnetic investigations alone, such investigations are of great help in the interpretation of data gained by other geophysical methods.