On today's program: The fallout from the destruction of the ancient Juukan Gorge caves at mining giant Rio Tinto continues with the resignation of two members of its board. Rio's chairman Simon Thompson and non-executive director Michael L-Estrange both stepped down this morning ahead of its annual shareholder meeting. Last year, Rio destroyed two 46-thousand year old caves in the Pilbara region against the wishes of its traditional owners. The scandal has seen the scalps of its former chief executive Jean -Sebastian Jacques and two top executives. But will this clean out of management and the board lead to real cultural change for the Pilbara iron ore miner?