Jamieson, Fausset and Brown on Leviticus 2:4

4. if thou bring an oblation of a meat offering baken in the oven--generally a circular hole excavated in the floor, from one to five feet deep, the sides of which are covered with hardened plaster, on which cakes are baked of the form and thickness of pancakes. (See on Ge 18:6). The shape of Eastern ovens varies considerably according to the nomadic or settled habits of the people.