Tall tales and true: of Yorkshire moors and the byways of Surrey: White cliffs of Flamborough

There is a lighthouse perched high on Flamborough Head in case ships miss the mass of stark white headland jutting out into the bluest of blue seas. The white cliffs, stretching for miles in these parts, are almost entirely of chalk, and are as distinctive as the cliffs of Dover.

We had to find out what brought them here so we walked the Bempton and Flamborough bird trail watching, reading and listening.

There is, in warmer oceans, a microscopic marine algae shaped like a crocheted sphere that lives in the sea. It is called a coccolith. As each coccolith dies it sinks to the sea floor and decomposes. Into chalk. Over millions of years, back to when dinosaurs roamed the earth, millions of coccoliths rested one on top of the other, right here. They slowly compressed, became firmly enmeshed, and move as the earth moves. So, at a time when the earth around here raged, these solid chalk rock masses were pushed up above the sea to stand proud, tall and beautiful.

Today, satellites often sight and photograph great swathes of coccolith in bloom visible in different seas. Why they multiply and die so dramatically is not fully understood, but for tiny invisible living things they pack a massive chalk punch.

The precipitous chalk cliff faces here are pitted with caves and carved out burrows that offer a safe haven for all sorts of land life like stoats and voles, and sea birds including puffins, kittiwake, guillemots, fulmars, herring gulls, gannets, razor bills and shags. Today there are hundreds upon hundreds of gannets wheeling and squealing, avidly protecting their young on every vertiginous ledge before they head off to West Africa as winter comes.

When mature, gannets have pretty yellow heads and black splashed wingtips, a lovely contrast to their large white bodies. When they fly their wingspan is impressive. To feed, they tuck their wings in against their body, push their nostrils beneath their beak so they don't suck in water, then dive bomb for fish from about 15 metres in the air directly into the sea. It is an amazing sight that we first saw in Newfoundland, where we also found puffins. But the puffins have gone from here now, until next year.

More than 13,000 pairs of gannets nest here every year. This is the only mainland gannet colony in all of England. It attracts more than half the world's gannet population at this time of the year. Those looking for partners take time finding one, as they pair for life, like swans and barn owls. Gannets live a long life, about 20 years. They build their nests with anything at hand, thatch from the fields, rope left by fishermen, seaweed tossed up on the tide. Rangers once found a mobile phone stabilising one of the nests.

They have one baby each season and take turns caring for it. Interestingly, gannets big webbed feet can stretch to the size of a man's hand, and these are thick with veins pumping warm blood down to their fleshy tips, so, affectionately, they cup their feet around the new egg to keep it close and warm.

The young are dark brown in colour with white spots until maturity. They stay on these ledges for around thirteen weeks and eat constantly, greedily, more than their parents, and become so fat they cannot fly. When time is up, though, they have to make a long scary glide down to the sea surface where they sit unfed until they lose weight, start growing fluff and feathers, and learn to fly. Then off to warmer climes they go, to start the cycle all over again.