Piers have four basic components: piles or columns, girders spanning the columns, decking and the mass of struts and braces which give them both rigidity and much of their individual character.

Eugenius Birch's great genius was to apply Mitchell's screw piles to pier building.  Screw blades were fitted to the bottom of the iron piles and the whole thing was simply (?) screwed into the ground.

Jetting involves hollow piles.  Once it is in place, pass a tube down the hollow to the bottom.  Connect the other end of the tube to a water-pump (or tap!) and turn on.  Water is forced down into the sand, which boils up outside the pile, allowing it to sink gently down, preferably for 5 or 6 metres.