The group walked slowly to the top of the cliff, stopping to study the Culver Chalk Formation of the Early Campanian and the various beds from the Palaeogene above and to fill in our stratigraphical logs accordingly. Attention was drawn to beds above the chalk containing jarosite and aluminium rich minerals. A cobble bed with unsorted angular flints was identified as a possible river terrace deposit before a marine transgression. Glauconitic laminated sand (marine) had been deposited above, then yellow sand, which got redder as you dug into it and was possibly a soil horizon. We then looked at a cross bedded unit with hummocky/swaley cross stratification, composed of medium to very coarse sands and the occasional flint pebble, and containing Thalassinoides burrows. Then a silty peaty layer containing organic sulphur hinted at deposition in a low energy environment such as salt marshes. Further up, a blue clayey mudstone was avidly dug up for selenite crystals (in two bands). A pebble bed suggested another transgressive marine episode and this was overlaid at the top of the cliff by a layer of finely broken oyster and gastropod shells identified as the last bed before the London Clay.

We then walked along the cliff path to an area where a new housing estate had been built very close to the edge. All along the path, evidence of the instability of the cliffs was substantial in the form of cracks in the ground. During storms, spray reaches the top of the cliff, saturating the ground and promoting slips. As much as ½ metre of Chalk can be eroded away during a year. A discussion took place as to the choice of site for the development and a quick consensus was reached on its unsuitability. We then adjourned for lunch.

We finished our lunch on the cliff top, in the lovely sunshine, with the predicted rain staying away. From our excellent handouts we could see that we were going to start our afternoon walk in the Newhaven syncline, looking at the Castle Hill Flints.

We made our way back down the steep gully, and all met up at the bottom of the cliffs, where we were treated to the image of large white Chalk cliffs, with many distinctive layers of flint and all topped by Tertiary/Quaternary sediments.

These continuous layers of flint could be followed all through the Chalk and we were pointed to two particular layers that were going to be our marker beds for the rest of the afternoon. These were flint layers 4 & 5 within the Culver Chalk. They were distinctive because layer 5 was quite solid looking and layer 4 was more scattered.

All the chalks we were going to look at were deposited in the Late Cretaceous, and were extensively deposited all over Europe. We know this because marl horizons found in England have also been identified in France and further (a project that Rory was working on).

Within these chalks we could see fault patterns, the faults start to curve as it descends, giving a bigger offset at the base of the cliffs. Another movement feature that could be seen was horizontal laminations seen in the upper chalks. The likely cause was the Tertiary erosion of the cliffs and resettlement of the Chalk.

Within the Newhaven Chalk we saw different types of faulting occurring. These were conjugate faults, where two fault lines cross each other, making a big cross in the cliff face.

The afternoon was getting hotter and the tide was going out. As we walked over the wave cut platform and investigated the Newhaven Chalk underfoot, we could see that it contained large chunks of nodular flint in tubular shapes. Rory explained that these shapes were due to flint replacing the burrows of an animal, probably a crustacean. This sort of burrow is called Thalassinoides. You could follow these casts and could even see passing places.

Then it was a race to see who was going to be the first to find the giant fossil ammonite. It took a little while, I was still looking when it was found so I’m not sure who actually found it. It was about a metre across, standing proud of the beach, Rory saying that they could get even bigger, however, they were a bit weather beaten and you had to look closely to really see a shape, but I believed him.

On the walk back I was lucky to find a fossil, an echinoid from the Culver Chalk, this got everyone looking at their feet for the rest of the walk back to the cars. Patrick found a more relevant fossil, Offaster pilula from the Newhaven Chalk. Both were flint fossils and looked quite impressive, Rory said that there were many on the beach but these were the only two found.

The whole day went well – the rocks were interesting, the weather was great, the people were friendly and the tutor was fabulous. What more could you ask for on a sunny Sunday? The day finished off in the pub for a well earned drink. I would like to thank everyone there for making my first trip very enjoyable.