The petroleum production from the Rhine Valley is and probably will continue to be of very small importance. It has its place, nevertheless, in the history of oil because the outcropping oil sands have been exploited for some five hundred years. Here oil sands have been produced by means of mine shafts and galleries on a great scale since the start of this century.

From the geophysical point of view, this part of the Rhine Valley was cut deeply into an old Paleozoic shield in the midst of a heavy gravity anomaly which collapsed by down-faulting.

One of several oil-producing rift valleys of the world, the small Rhine graben valley, came to attention again in 1953 by the discovery of three new oil fields of little importance. Two types of oil are present which almost certainly are of different origin--one oil is of a mixed base attributed to a Tertiary origin; the other is of a paraffin base and seems to belong to the Mesozoic substratum in which the whole set of Cretaceous sediments is lacking. Some cases of migration of Tertiary oils into Mesozoic reservoirs and vice versa can be deduced from the chemical analyses.

Though big losses of oil from Mesozoic beds probably occurred during the Cretaceous uplift, there are still discoveries to be expected from deep fault blocks in the southern zone of the valley, but they are difficult to locate. In the northern zone, Tertiary discoveries are much easier to make, but also in this part there should be new possibilities in Triassic formations.