In Red Wharf Bay we show the students the very old rocks of central Snowdonia (Cambrian to Silurian) and the volcanics rocks associated by subduction. In Red Wharf Bay we show them the slightly later rocks, from when the continents had stopped colliding and the rocks deposited were mainly shallow water carbonates. We have to fill in some geological periods from which there are no sediments in that bay. In red Wharf Bay this shows itself as glacial sediments from the last glaciation lying directly onto Carboniferous limestone. A gap of 360 million years!
My students were rather keen. When there was some time to spare some eagerly started to collect nice rocks, shells and gastropods. I failed to find a nice crinoid for one of them. And the sun came out about halfway into the trip! It was a nice morning out!
One of the other groups on the carbonate platform
That same group admiring something from a distance