Thanks to all who responded to my question. I suspect the most probable situation was that the ground was frozen. I live in Minnesota. My mother died in December of 1974 and she was buried in March (although the death certificate does not reflect that). Walsh county, ND is 200 or so miles north of where I live. Good point that in 1920 the equipment wasn't the same is in 1974. The death certificate said the cause of death was old age. She was 81. Vickie M