Addendum to Forty-Eight[
This arm of the sea is called the Ria de Arousa and the Island of Arousa has a clear Megalithic outline best summed up in this picture. ]
However, the link with the mainland is an entirely modern bridge so it may be that the actual entrepot is the O Grove peninsula to the south which would appear to have been a tidal causewayed island in the distant past, at least if this description can be so interpreted:
Located on the entrance of Arosa´s estuary, Ogrove is a well known tourist resort, appreciated for its natural beauty, mild climate and exquisite shellfish. Surrounded by the lsles of Salvora, Ons, Arosa, and touristic San Xenxo, the old Celtic land of Ocobrix has been an isle until recent ages, when ocean streams created a sedimentary union with the Salnes peninsula.
But an even more intriguing candidate is Cortegada Island which is right at the mouth of the River Ulla leading up to Santiago de Compostela. This is a true causewayed tidal island.
The island is connected to the mainland via a tidal causeway, i.e. a trackway covered at high tide and revealed at low tide. The causeway is 189 meters wide
This is a machine-translation and presumably means '189 metres long'. However, it is the highly peculiar hydrology of the island itself that would seem to point to the sometime presence of Megalithic engineers:
It has two main fresh water sources: a seasonal lagoon and subterranean fresh water. This last source is peculiar since the island is surrounded by salt water, everybody can dig a well without effort even near the beach, without the need of digging further than several tens of centimeters, around ten inches at the most.
And the machine translation of the following rather adds to the air of mystery:
The island is almost flat, its highest elevation is 22 feet high. It has an area of 54 hectares of land with a rectangle shape. Due to the large amount of water in the terrain, it flows in streams everywhere or stay quiet in ponds and puddles. The water drips, cover and soak the plants, rocks, soil, logs, moss etc. and still the water is being impassable the island during heavy rain.