Aturning point is defined as

information relating to a topic.
information supporting a viewpoint.
a significant statement of an event.
a significant event in history.

explanation: we can only guess at how our actions may be perceived in the future. doing something really big like killing lots of people, saving lots of people, affecting the lives of lots of people is a sure fire way of being remembered in historical records. we can also make a difference in the history records by being a small influence on something bigger, whether that is as a civil servant, scientist or artist.

of course you could argue that we all affect history just as tiny cogs in a   bigger machine.

if you mean how do people influence our opinions of things which have already happened, then simply by writing a book which looks at things form a different perspective and trying to convince people that this perspective is more accurate or truthful. people do it all the time i.e. richard the third was a terrible or was he? plenty would disagree, it's just that their views aren't the most widely known.n:

answer; i believe the correct answer is (the willamete valley);

well first we can compare on what the slave masters ate and what the slaves ate well the masters ate fancy great food like chicken rice mash potatose and stuff like that and slaves ate well food that your not suppost to eat like the weird parts of turkey and chicken and slaves master chilled beat and eat and slaves work get beat and get little of sleep there you go