After two weeks of work with hardly any progress Cormelian decided to secretly sme of the green stone under the granite in her aprons o that her husband would not notice. However, one day Cormoran did notice and angrily instructed his wife to return the green stone to the mainland. On her way back down the causeway, the apron strings snapped and the green stone tumbled to the ground and Cormelian decided to leave the stone there. The pile of green stone is now called Chapel Rock and the ferry sails from this point to go to St Michael’s Mount at high tide.
Eventually, Cormelian and Cormoran finished the stronghold, which towered high above them. Upon seeing the Mount the villagers cried: ‘Who will stop this giant? None of our cows or sheep will be safe now that Cormoran can take them to his stronghold! We’ll starve!’
Jack, a local boy, was fed up with the bad-tempered giant stealing his livestock. He decided to act. One night, he crept out and set a trap to teach the giant a lesson; he dug an enormous pit near the causeway and covered it up with straw and branches to hide it.
When it was ready, Jack walked up to the front of St Michael’s Mount and blew his horn. Outraged at being woken up stormed out of his stronghold and chased after Jack who was taunting him. Jack sped along the causeway and when the big clumsy giant couldn’t stop in time, he fell down the pit. Jack walked to edge of the pit and peered down. ‘I hope this will teach you a lesson!’ he said. ‘Giants shouldn’t steal our livestock!’
Cormoran was killed by a blow from a pickaxe or mattock. After filling in the hole, Jack retrieved the giant's treasure. A rock was placed on the burial site and this rock is called Giant's Grave.