of a great alluvial plain, occupying what is now the southern half of the North Sea, and stretching across to Holland and Denmark. If we go beyond the Dogger Bank and seek for answers to these questions on the further shore, we find moorlog washed up abundantly on the coasts of both Holland and Denmark, and it has evidently been torn off submerged ledges like those of the Bank. Numerous borings in Holland give us still further information, for they show that beneath the wide alluvial plain, which lies close to the level of the sea, there exists a considerable thickness of modern strata. At Amsterdam, for instance, two beds of peat are met with well below the sea-level, the upper occurring at about the level of low-tide, the lower at a depth of about 50 or 60 feet below mean-tide. That is to say, the lowest submerged land-surface is found in Holland at just about the same depth as it occurs in England, and probably on the Dogger Bank also.
Below this submerged land-surface at Amsterdam are found marine clays and sands, which seem tp show that the lowest "continental deposit," as it is called by Dutch geologists, spread seaward over the silted-up bed of the North Sea; but no buried land- surfaces have yet been found below the 60-foot level anywhere in Holland.
This appearance of two distinct and thick peat-beds, underlain, separated, and overlaid by marine
