The bottom of the ark may have been made out of large logs to give it extra stability. It was a particularly important feature, as it provided needed ventilation and illumination. The exact type of wood used is not known. It may have been teak, cypress, or some other hard or hardened wood. It is believed that some oil may have existed before the flood, produced from non-biological sources.
Most oil is believed to have formed from plant material uprooted and buried by the flood.