Found log burning internally, how is that possible?

Question

I was on a flat beach with 10-20mph winds, and I found a stump and pieces of driftwood that looked like it was internally burning. There was no flame, only sparks, and the rings inside were glowing fire-red, meanwhile the outside bark wasnt and it was unburnt.

In: Chemistry

Answer 1

Did you stumble on a Swedish Torch?

https://en.m.wikipedia.org/wiki/Swedish_torch