Strange terrain bug - Random desert chunks overlapping world terrain

I entered a random seed, and got this. At first it seemed awesome, as there was an abandoned mineshaft right under the first desert chunk I saw (First time I see a mineshaft within 50 blocks distance of spawn). A weird thing about the desert: They had perfet straight stops that looked as if someone built it, it didn't fit the terrain and seemed to be overlapping, and in several parts it looks like a mountain was cut in the middle.

To see it yourself, the seed is 4919780781367771259