Folklore and Legend from the locals

My family is from the Huejuquilla, Jalisco, Mexico area.

From the locals, I have often heard about mysterious flares of light that just suddenly appear out of the gound at night in the country side.

What could they really be? Signs of natural gas deposts in the ground or oil?

And another folklore by the locals is the saying that there used to be a race of giants. I guess from the discovery of giant bones that wash up when there are heavy rains.