The most active period in Germany's 85 years of oil-field development was the decade that ended with the close of World War II. Twenty-eight oil fields were discovered during that period and 62 per cent of Germany's total cumulative production obtained. About half of the new fields were found in the old Hannover producing district, from which has come more than three-fourths of all the oil produced in the country. The oil from the earliest of these new fields together with that obtained in extensions of the old Nienhagen field resulted in the annual crude production being more than doubled between 1935 and 1940. In the latter year an all-time peak of 7,393,309 barrels was reached. In spite of the discovery of II fields since, the production declined after 1940 and was onl 5,053,552 barrels in 1944 and 3,838,709 barrels in 1945.

Most of Germany's crude oil comes from Lower Cretaceous and Jurassic formations on the flanks of salt structures which are the result of a combination of tangential folding, occurring during the late Jurassic and Cretaceous, and the upthrusting of Upper Permian salt beds. The oil in the Central Hannover district is in most places confined to narrow belts of tilted strata on the flanks of the salt structures, the thin producing sands being sealed in by uncomformities and faults.

Only one important field--Reitbrook--has been found on the crest of the many deep-seated domes that have been discovered by geophysical prospecting in the region north and northwest of the Central Hannover district. It was formerly believed that large production would be obtained from the Hannover oil sands on the crest and flanks of these domes. Many of them have as yet not been adequately tested, but of the two score or so drilled only four have yielded oil chiefly from Upper Cretaceous chalks. The poor showing made by these domes evidently is due to the absence from the region of the Lower Cretaceous and Jurassic oil-bearing formations. The Pompeckj uplift, from which these formations were eroded, extends over a much greater area than was formerly recognized.

Another disappointing development has been the failure to find important new production in the Middle Zechstein dolomites in central Germany. The discovery of oil from these dolomites at Volkenroda in the Thuringian basin in 1930 has led to no other commercial field being found in the region.

These unsuccessful developments have been offset to some degree by the new discoveries at Heide in Schleswig-Holstein and near the Dutch border in western Germany. In the Heide fields oil is produced from Middle Zechstein dolomitic limestones and a pre-Neocomian scree breccia on the west flank of an elongate salt structure with a core of Rotliegend salt-bearing strata.

The three fields discovered near the Dutch border in 1942 and 1943 produce from Lower Cretaceous sands and shell beds. They are situated on low folds unrelated to salt tectonics. These new developments, together with the possibility of discovering deeper sands on the flanks of salt structures, and the search for gentle folds between the salt structures, offer the best prospects of new discoveries. The Munich basin probably is the only region outside of the producing districts that justifies exploratory work.