The so-called "giant trace" refers to the foot of the Buddha statue.
Outside the gate of Shengshou Temple in Baoding Mountain, there is a half-acre pond called "Buddha Trace Pool". There are a pair of big footprints carved on the bottom of the pool, which are 1.8m long and 1. 1m wide. This is the "Buddha Trace", the so-called "Giant Trace". It turns out that there was no idol sculpture in early Buddhism, and worshipping the Buddha in Baita was a ritual Buddha. "Records of the Western Regions of Datang" states: "The Buddha left a mark on the stone of Mojietuo." Tang Xuanzang once worshipped Buddha's feet in Tianzhu, and made a detailed account of its shape and origin.
There is a story about Buddha's foot in Dazu.
It is said that Sakyamuni has achieved positive results under the bodhi tree and is going to nirvana. He said to Ananda, Ye Jia and other disciples, "I want to become a Buddha and a ancestor after my death and go to the western paradise." Hearing this, the disciples all clamored to go with Master. Sakyamuni said, "No, you must continue to practice, and you can't go to the West until you are fully conscious." Disciples go after Master whenever they are unwilling to listen. Sakyamuni forbade them to follow, so he drew his forefinger in front of him, and immediately a big river appeared in front of him, separating him from his disciples. Standing by the river, Sakyamuni saw the poor disciples on the other side and couldn't bear to leave them at once. Especially before farewell, I have no nostalgia for this world! ? So he stood by the river for a long time, leaving his deep footprints on the river bank. In the end, he was nirvana, but the footprints he left were still there, which became a "holy relic" of Buddhism.