Slate Marmot asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
how were the cliffs of moher formed ?
The Cliffs of Moher, on Ireland's west coast, are almost 400 million years in the making — let's see how stone became sky-high wall.
Three hundred twenty million years ago, this spot wasn't cliffs at all — it was a river delta, dumping sand and mud into a shallow sea.
Layer after layer, season after season, sand and mud piled up and pressed into rock — that's why the cliff face shows stripes.
Over deep time, Earth's crust pushed these layers upward, lifting the old seabed high above the waves — that's called uplift.
Then the Atlantic Ocean took over, smashing waves against the base year after year, chewing away softer rock and leaving the hard layers standing tall.
Today the cliffs stand over 200 metres tall in places — a slice of ancient riverbed, lifted up and carved by the sea, still eroding a little every year.
An ancient river's mud, lifted skyward, then sculpted by the sea — that's how the Cliffs of Moher stand today.