Cotidal lines in the North Sea

Also in April I read a book about how lunar cycles influence living organisms: "Moon Rhythms in Nature" by K-P Endres & W Schad. There I found this map which shows how tidal waves in the North Sea move counterclockwise in circles. High tide runs along the east coast from Edinburgh to Bridlington. An hour later it arrives on Spurn to then turn eastwards to another continent - to the shores of Holland, Germany and Denmark - da capo al fine.