The recent BBC News article Why India Wants to Turn it's Beaches into Nuclear Fuel includes the passage:
The tropical beaches of India probably bring to mind sun-dappled palms, fiery fish curries and dreadlocked backpackers, but they also hold a surprising secret. Their sands are rich in thorium – often hailed as a cleaner, safer alternative to conventional nuclear fuels.
The country has long been eager to exploit its estimated 300,000 to 850,000 tonnes of thorium – quite probably the world’s largest reserves – but progress has been slow. Their effort is coming back into focus amid renewed interest in the technology. Last year Dutch scientists fired up the first new experimental thorium reactor in decades, start-ups are promoting the technology in the West and last year China pledged to spend $3.3bn to develop reactors that could eventually run on thorium.
The caption to a stock image of a beach says:
Kerala's beautiful beaches hold 16% of India's thorium reserves, a major potential power source - if only scientists can find the right way to exploit it.
Question: why would India have so much thorium on it's beaches, apart from the fact that India has so many beaches of course?