Norfolk Cliff Clay
On 23rd July I took a whistle-stop research trip to the Norfolk coast for two days. The plan was to drive the coast road from East Norfolk round to North Norfolk, scoping out potential sites, re-familiarising myself with the basic geography, and gathering a few materials along the way. In all my years growing up in Norfolk, I don’t remember ever driving the coast road in such a long stint, and it was lovely to connect up places and memories after so long away.
I had chosen a Spring Tide, with the first low tide of the day at dawn. The sky as I approached Happisburgh (pronounced “Haze-borough”) was on fire and, with not a breath of wind, the sea was like a millpond. For all its natural beauty, Happisburgh is a troubled place; both branches of Beach Road stop abruptly at the cliff edge as if just torn paper. - The barriers and warning signs seem a poor memorial to the houses and memories which have fallen into the sea only in very recent years.
Having read up on the geology of the Happisburgh area, I knew to expect a thick layer of dark Till or Boulder Clay at the base of the cliff, with a thinner layer of much lighter Ostend Clay sandwiched between the Till and the uppermost, considerably thicker, layer of rusty sand and gravel. The strata were strikingly clear, (if not exactly as the books described them) and I walked north along the beach to find a freshly collapsed section of cliff. Having chosen my spot I checked the ‘plasticity’ of this pale grey gunge by softening it a little using seawater. Suitably convinced, I managed to select great clumps of the stuff from the tangled heap at the base of the cliff, supplementing this with a thin section trowelled from the original seam. With what I naively estimated to be around 10kg in a bag slung over my shoulder I trudged back to the car. - The bruises over my collarbone the next day suggested my estimate was way off, and I later learned that the dry weight alone was over 14kg(!)
Making sure to take the precise Longitude and Latitude reading for the site, I took a moment to enjoy the silence, before continuing along the coast.
Once back at the studio, I laid out my cache in the sun to dry. Noticing just how smooth it was, and unsullied by grit, sand or stones, I thought I’d risk firing a small amount of it unrefined. Potters are interested in the ‘Plasticity’ of clay, that is to say it’s ability to be shaped and moulded without cracking. A typical test of plasticity is to make a short sausage or coil of the clay in question, and try to loop it into a ring. - Some say even tie it into a knot. Clays which are ‘short’ will crack clean through, while a perfectly plastic clay would not even exhibit surface cracks. I was just pleased to keep this little ring intact, and pinched a tiny bowl with the remaining scrap. To my surprise, she fired to 1000°C with no trouble, and revealing a pale pinkish cream colour, confirming that the clay holds very little iron oxide.
Of course, never content with success, and with the documentary proof taken in photographic form, I immediately put them back in the kiln on an impossibly high firing (for a ‘wild’ clay) up to 1260°C… and here is what happens if you do that… it melts completely!!
Far from this being a failure, it is a new piece of information in the puzzle and, perhaps, the beginnings of a rather nice Norfolk stoneware glaze, or reactive slip.
Ostend Clay taken to 1260°C (it melted!)
