A world created with this mod has four layers: ice crust, ocean, rocky mantle, and iron core. The ice crust is the uppermost layer and has ice instead of stone. The ocean is beneath the ice and consists of just water. The rocky mantle is beneath the ocean and contains all the ores from default. The iron core is beneath the rocky mantle and has steel blocks instead of stone. To get a good idea of Europa's composition, look [here](https://www.google.com/search?q=composition+of+europa&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi9zqzHwv3iAhVLmeAKHfqdAl4Q_AUIECgB&biw=1920&bih=949#imgrc=7Zk0KJtKcp4xZM:).