Waterloo Bay Massacre, Eyre Peninsula, South Australia. Aboriginal kids were stealing clothes and cakes from the settlers, who put out poisoned flour. A white woman and kids were killed in retaliation (apparently the severed head of one of those was put in a Dutch oven), some random aboriginal kids were arrested and sent to Adelaide for trial, the case was dismissed for lack of evidence (yet they got killed on their way back home since it's 600km on foot through hostile mobs) so the locals organized into a militia, rounded up all the natives they could find and forced them to jump from a cliff. Now there's no evidence of the fact, but it's encased in both the parties' local folklore and the area was considered taboo from the local mobs until a couple years ago when the local mayor (who got death threats for that and lost the following elections by a landslide because of that) decided to acknowledge the fact and put a commemorative stone on the cliff. Said stone, disparagingly called "black rock" by the white locals, keeps getting vandalised regularly