Obscure Home Plate

Question
I been involved in softball for many years and have never seen this happen. I can not find any rule references to what happened and I want to know if the umpire made the correct call.

Girls 14 & Under Slow Pitch.  With runners on 2nd & 3rd, a batter gets a hit to center field.  Both runners advance.  A throw to home is made by a fielder. Runner from 3rd slides into home, contact is made with the catcher and the catcher drops the ball. Umpire calls the runner safe.  Home plate is now covered with dirt and the runner and can not be seen.  Before the either the catcher or the runner who just scored can move out of the way, the runner from 2nd slides into home and appears to touch home which she could not see.  As part of her sliding action, she attempts to avoid a collision with her teammate. The opposing coach yells that she did not touch home plate. (Little bit of umpire influencing) With the runner who scored still on the ground and covering most of home plate, the second runner touches the ground near where she thinks home plate to be.  She gets up and as she is returning to the dugout, she is tagged by the catcher and called out by the umpire for failure to touch home which by now no one could see. Basic question, is it the responsibility of a runner to know where home plate is located if it is completely covered with dirt and or is obstructed in part by a teammate?

--Thanks for your time!!

--Bob Blom, Madison SD

Answer
Hi Bob,

I'm just wondering why R1 was laying there so long and didn't get out of the way?  That could be a problem...depending

This is a htbt kind of play but much like the batter's box where the lines are gone, I'm giving any benefit of the doubt to the runner.

Mark