From Lostpedia

Bram uses ash to repel the Monster

Ash circles are used as a measure of protection against Jacob's nemesis in his black smoke form. Along with bamboo thickets and the DHARMA Initiative's sonar fence, this is one of the only methods known to stop the Monster's attacks. Several ash circles have been seen on the Island.

Appearances

Jacob's cabin

An ash circle surrounded the cabin that allegedly belonged to Jacob. When Ben encountered it, he was careful to step over it without disturbing it. Inside, they encountered a man Ben claimed was Jacob. ("The Man Behind the Curtain") Later, when Hurley encountered the cabin, he did not see the ash circle. When he looked inside, he saw Christian Shephard and a face similar to the man Ben said was Jacob appeared in the window. ("The Beginning of the End") Shortly afterwards, Locke found the circle, but the cabin was missing. ("The Economist") When Locke, Ben, and Hurley trekked to the cabin for new orders, they did not appear to find the ash circle. Inside, Locke met Christian, who said he would speak on Jacob's behalf. ("Cabin Fever") When Ilana, Bram, Frank, and the rest of their party found the cabin, Bram noticed the ash circle was broken in one spot. This alarmed both Bram and Ilana, who exercised caution as she entered the cabin and found no one inside. ("The Incident, Parts 1 & 2")

Bram

Ilana, Bram, Frank, and their group arrived at the remains of the Statue of Tawaret with the body of John Locke, which they showed Richard. After several delays, Bram became impatient and forcibly entered the statue with three men and Ben. Inside, Jacob's nemesis (in the form of Locke) revealed Jacob was dead. This prompted Bram's men to shoot at him; the nemesis transformed into his smoke form and attacked. While his men were being killed, Bram produced a pouch of ash and sprinkled some in a circle around himself. The Monster was unable to touch him in this circle, but it instead brought a chunk of the ceiling down, knocking Bram out of the circle and allowing him to be killed. ("LA X, Parts 1 & 2")

The Temple

At the Temple, Hurley revealed to Dogen and Lennon that Jacob was dead. This alarmed them, and the Others began precautions, sounding alarms, launching a flare into the sky, and sprinkling ash circles around the courtyard. When asked why they were doing this, Lennon said it was to keep "him" out. ("LA X, Parts 1 & 2")

Unanswered questions

For fan theories about these unanswered questions, see: Ash circles/Theories

• Why does creating an ash circle stop the Monster?
  • Is there anything special about the ash that is used, or will any ash work?
  • What connection, if any, exists between the ash circles, the sonar fence, and the bamboo thickets?
• Why was Jacob's cabin surrounded by an ash circle?
  • Was this ash circle used to keep Jacob's Nemesis in or out?
• Who created the ash circle around Jacob's cabin?
• When did the break in the ash circle around Jacob's cabin first occur?
• What or who caused the break in the ash circle around Jabob's cabin?
• How did Bram know to create an ash circle to stop the Monster?
• If the ash circle provides protection from the Monster, why isn't it already surrounding the Temple to protect it's inhabitants?