Incised Shaman Rock? Mammoth Tooth Fossil?

On Tuesday at the Texas City Prairie Preserve, I was walking along the gravel road between the education center and potting area when I saw this rock among rocks.

The lines etched on the rock were all over the surface and accented by a white coating in the grooves.

Always wanting to find that hidden treasure or prehistoric tool, my imagination ran wild with ideas of its origination and utility!  I asked the others at the potting table if they had seen anything like it...."No" no one had.

At home I took the photos seen above, attached them to an email to Dirk Van Tuerenhout at the Houston Museum of Natural Science who forwarded the inquiry with rock photo to the resident geologist.

The explanation for the "groovy" rock:

 "The chert photos you sent to Inda are certainly the common variety of banded chert. 

Ground water stains the rock with manganese where the chert is more porous.
People bring this into the Houston Gem and Mineral Soc all the time and are disappointed when the inside shows a nearly uniform white color.

This is a natural phenomenon and was not aided by humans."

: )

Marilyn