A very old an unusual Burial Ground in Washington County Pa leaves more questions than answers

I travel the back roads of Western Pa. and in doing so I often run across small family burial grounds
one of the most unusual  is along US 40  The National Road  outside Claysville  its one of those ones you blink your eyes and you miss it. Still maintained  unlike others I have encountered which have gone back to seed after all family members have died and or moved away .This cemetery has fresh flags for its veterans every spring.
But has many unanswered questions as the graves are unlike any I have seen before.

Almost all of the graves are raised up tablets.
Now I have seen the tablets flat on the ground at a Moravian Cemetery in Bethlehem Pa but to my knowledge no Moravian  settled in Washington County . It has also been suggested they might be Jewish but this is not the case either the names readable are German or Swiss in nature   and Jewish graves are not raised in this manner. they date from very early 1800's so they had to be early settlers  but every one I ask in area have no idea the place is even there its so well hidden .So many of the tablets and stones  can not even be read at this point they have so badly eroded.

Or if they did know no one knows anything abut who is buried there.  I have not had time to run down the names and hope to do so some day and find out the story of these graves and how they came to be . But for now they rest peacefully hopefully for eternity as many a grave yard has been damaged in W. Pa. by those who have no respect for the dead. I have no tolerance for those who would desecrate such a place and will not hesitate to turn them in when I spot them.