In almost all of the hard stones I have ever found that were marked, the numbers or hatch lines were tapped in with a tool and not chiseled. If you examine the marks closely it appears like punch marks close together. The markings on the softer stones like sandstone and limestone were chiseled or scratched in. The markings below on the stone are a series of punch marks.

Thanks Jerry
Thanks Jerry, I see it now.
Sorry Moe
I am sorry Moe if I made you regret posting this.
Jerry helped me to see the 4 & then you did too.
Personally I am glad you posted this.
It just goes to show how important local experience is.
Thanks, Brad
Just sayin'
I opened this thread up on my droid today. The smaller images made something stand out.
I put the soil line in to orient the stone a bit.
now look at these two.
this is what caught my attention....

just sayin'
btw...
I don't know who that goofball was that hacked my account last night and made those other posts... boy was he balled up....
😉
Rankin-good catch
That does looks like a 4.
Now I have two on the stone!
The stone was all under the ground. It was found by poking around for 10 minutes and hitting it about 2640 due north of the section corner to the south. So the soil line would have been above it. It had been looked for a number of times over the years so I think it had been buried for at least 50 years which was about when the bars started to get set.