Strange patterns in the grass!

I was walking back home from my sheep farm in MCPE 1.1.0 when I noticed a super strange pattern on the ground. There were several different coloured sand-like blocks, and some areas were pitch-black. Also, it looked as if some blocks led straight to the void, yet I stood on them as if there were blocks there. Never seen this before, really freaked me out. When I mined or placed another block next to the glitched one, it would turn into normal grass. Also, some grass blocks had snow on them, even though I'm in a plains biome.