(Reuters) - Mining giant Rio Tinto Ltd destroyed two ancient and sacred rock shelters in the Pilbara region of Western Australia as part of an iron ore mine expansion in late May.

The blasts, while legal, deeply distressed the traditional owners and led to a public outcry and national inquiry, ultimately costing three top executives their jobs. They also increased investor pressure on the industry to address heritage management practices.

The parliamentary inquiry is due to report Dec. 9.

May 24: World's biggest iron ore miner destroys the rock shelters in the Juukan Gorge, one of which showed evidence of continual human habitation dating back 46,000 years.

May 27: Rio Tinto issues a statement saying it is sorry that the "recently expressed concerns" of the Puutu Kunti Kurrama and Pinikura (PKKP) people did not arise during discussions. PKKP on June 5 rejects that characterisation and says the significance of Juukan Gorge had long been emphasized.

June 11: Rival BHP Group says it would not disturb any sites around a planned $2.9 billion South Flank expansion in Western Australia without further study and consultation with traditional owners to better understand the cultural significance of the area.

June 11: Australian Senate refers the Juukan Gorge incident to the Joint Standing Committee on Northern Australia for an inquiry.

June 12: Rio Tinto Chief Executive Jean-Sébastien Jacques addresses the incident for the first time, and pledges full cooperation with an Australian government inquiry.

June 19: Rio launches an internal board-led review and says it will look at ways to improve its internal processes and governance following public outcry.

Aug. 7: Rio did not tell the PKKP about three alternative mine plans, its CEO tells the parliamentary inquiry, despite saying it had won fully informed consent for blasting.

Aug. 7: Fortescue Metals Group says it will review plans at an iron ore mine in Western Australia after an Indigenous group said a planned expansion threatened sacred sites, including a 60,000 year old rock shelter.

Aug. 24: Rio's board-led review finds procedural faults and cuts the short-term bonuses of some senior executives but stops short of leadership overhaul. The review is not well received by the public and investors who say it lacks accountability.

Sept. 11: Bowing to stakeholder outcry, Rio parts ways with its chief executive and two deputies.

Oct. 29: Investors worth $10.2 trillion step up pressure on mining companies, write to boards of 78 miners asking for more information about how they manage their relationships with First Nations people.

(Reporting by Shruti Sonal in Bengaluru; Editing by Lincoln Feast.)