The world is not a normal world. It is custom, and has ores, animals, minerals, and trees distributed based on the biome. Here is a chart that shows everything:

Realistic Biomes-0

Green means more common/grows quicker, while red means rare/grows extremely slow. Not having any dot means the biome does not have or can not grow that item.

The rarity of colors, from lowest to highest, are as such:

Red, Orange, Yellow, Blue, Green
For example, here is what savannas have, based on the above chart:

  • Excess Coal, an average amount of Iron ore, and a higher then average amount of Gold ore.
  • Some Granite
  • Rare Oak trees, mostly Acacia trees, and sometimes there are Birch trees.
  • Only wheat and cacti grow here, with wheat growing slightly faster then cacti.
  • Many horses can be found, along with a few chickens, and rarely sheep.