What is more erodable, boulder clay or chalk?

Question

I'm writing a report for Geography at school, and we need to say how to defend the Holderness coast. Area One, Flamborough Head, is made up of chalk cliffs. Areas Two and Three are boulder clay. Should I let nature take its course at Area One?

Answer 1

the clay it turns to soup when it gets wet,

the chalk dissolves which is a much slower process

Answer 2

I would say that they are about even, though boulder clay may be a bit more erodable than chalk.