Natural or artificial Incised striations on portable creek rocks...how to tell?

[nunyabiz111]

Any quick opinions on these two? Found along waterways involved in past log driving operations (north-western NB, Canada)


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[nunyabiz111]

Both rocks measure approximately 6''h x 8''l x 2''w

 

[Quinoa]

Looks like veining/intrusion type lines from calcite or something more readily eroded than the host rock. They will use natural cracks/fractures similar to how this occurs but they generally will just look like a single large "X"