"rock-like" (petra, "a rock," eidos, "a form, appearance"), is used of "rock" underlying shallow soil, Matthew 13:5,20 , RV, "the rocky places" (AV, "stony places"); Mark 4:5 , RV, "the rocky ground" (AV, "stony ground"); Mark 4:16 , RV, "rocky places" (AV, "stony ground").
Note: In Acts 27:29 , AV, the phrase tracheis topoi, lit., "rough places," is translated "rocks" (RV, "rocky ground").