Country diary: where did house martins live before there were houses?

Flamborough, Yorkshire: Against the brilliant white of these cliff faces are some tiny mud cups. And one was still in useThe coastal cliffs at this place are so intensely white that, with sunlight rebounding on three sides, the chalk face in Selwick's Bay is almost blinding. It's no more than 20m high here, but farther north at the RSPB's Bempton reserve, with its breeding colony of 400,000 seabirds, the sheer rock rises five times higher.It is difficult to process how a scene of such dramatic scale could be made by something so small, because, while there may be a touch of grandiloquence in their name - coccolithophores - it refers to algae. More than 100 million years ago these monocellular phytoplankton wafted in warm seas, and as they died they drizzled to the seafloor, adding their calcium-rich coccolith corpses to an immense, accumulating hoard. At Bempton's sublime cliff-face, that collective graveyard is 100m deep - proof that the planet's real magic can be assembled, had we but world enough and time, in the most mundane of ways. Continue reading...