Lining or casing well bores goes back to the early days of hand dug water wells when rock and dry masonry were used to line water wells to keep unconsolidated surface soil and rock layers from caving in over the exposed water bearing formation. Small diameter holes were drilled in China prior to 6000 BC to recover brine for salt extraction. These small holes were cased with bamboo. Hollowed-out logs have also been used to case shallow bore holes. During the evolution toward modern day oil field casing, tin tubes with soldered seams and joints have been used as well as iron pipe held together with rivets.