A little of geology (riddle)

Why in area, British island south, brittany and north french, belgium,
netherland, north germany, the ground goes down ?

It's not the sea which goes up, this is really the ground which goes down

See the West Frisian Islands, it's clear

At the bottom English Channel we found dolmens

In brittany on the beach we found fossilised forests

The question is interesting because, the answer is difficult to find
with internet

Le 02/12/2017 Ã* 18:46, Sylvain a écritÂ*:
Why in area, British island south, brittany and north french, belgium,
netherland, north germany, the ground goes downÂ* ?

It's not the sea which goes up, this is really the ground which goes down

See the West Frisian Islands, it's clear

Â*At the bottom English Channel we found dolmens

In brittany on the beach we foundÂ* fossilised forests

The question is interesting because, the answer is difficult to find
with internet


There is no one trying to find

Should I give the answer or do I let you to find ?