What would be a good thesis statement for this?

Isolation is a horrible thing. Many consider the Lord of the Flies to be representative of the time during which it was written. Give two ways in which the very geographic nature of the island impacted the fight for power and control.

I really don't feel it had that impact or meaning, in what ways do you feel it did

I honesly don't. Our teacher thinks for example castle rock affects the boys behavior and makes them feel more powerful

You have plenty to go with in developing a good thesis statement.

From bookrags --

Castle Rock: The fort Jack adopts as the base for his tribe. Roger drops a boulder onto Piggy here, killing him instantly. The conch is also shattered here.

Creepers: The long vine-like plants which encompass the island.

Fruit: The original food source for the boys; Jack however, insists that they need meat instead. Simon hands out fruit to littluns when they cannot reach the higher branches of the fruit trees.

Granite Platform: The meeting center for Ralph's democratic assembly.

Mountain: Site of the original signal fire. As the myth of the beast grows, this is the location where it is thought to inhabit.

Pig-run: Path made by the pigs on the island and later used by boys as a trail up the mountainside to investigate the presence of the beast.

Sand Castles: Built by littluns Percival, Henry and Johnny, these sand castles are destroyed when Roger and Maurice throw rocks at them.

SparkNotes: Lord of the Flies --

The island itself, particularly Simon's glade in the forest, recalls the Garden of Eden in its status as an originally pristine place that is corrupted by the introduction of evil.

I think the island's geography illustrated the power struggle more than influenced it.