Art collective Liberate Tate - which campaigns against arts sponsorship by oil companies - held an unsanctioned performance in Tate Modern's Turbine Hall on Saturday and Sunday.
Performers arrived at Tate Modern at high tide on the Thames at 11.53am on Saturday, dressed in black.
Starting from the bottom of the ramp at the western end of the turbine hall, veiled participants took it in turns using charcoal to transcribe quotes from a selected bibliography of books onto the floor of the gallery.
The 'Time Piece' performance ended 25 hours later at Sunday lunchtime's high tide.
Eva Blackwell of Liberate Tate said: "I've been to a number of Tate turbine hall installations, but this is the first time I've performed in one.
"This is a textual intervention. We're filling the Turbine Hall with a tide of ideas and narratives of art, activism, climate change and oil."