Resumen
It will be useful to show first a sketch of the situation of our low lying area with regard to the North Sea (Fig. 1). We might idealize the North Sea in the shape of a rectangular pocket, nearly 400 miles wide and 500 miles long, open to the Atlantic in the line Duncansby (Scotland) - Bergen (Norway). For its size the North Sea is relatively shallow. The depth is of the order of magnitude of 60 m. The funnel-like Southern part, between England and the Netherlands, is not more than 40 m deep. The average width of this part is 250 miles.
Authors retain copyright and grant the Proceedings right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this Proceedings.