If you missed the last two segments of Saturday Extra with Geraldine Doogue on Radio National in March, there’s still time to catch up. Hear Grace Karskens talk about her research on early Sydney and the ‘first frontier’ of the Hawkesbury-Nepean River, and Billy Griffiths discussing deep time and the history of Australian Archaeology:

Grace Karskens: http://www.abc.net.au/radionational/programs/saturdayextra/historian-grace-karskens/9581686

Billy Griffiths: http://www.abc.net.au/radionational/programs/saturdayextra/deep-time-dreaming/9555046

Image: View of part of Hawkesbury River at 1st fall and connection with Grose River N.S. Wales, 1809; watercolour by George William Evans? Mitchell Library, State Library of New South Wales.