3. A minimal volume of 5 ml of a pooled BAL sample is needed for BAL cellular analysis. The optimal volume is 10 to 20 ml. It is acceptable to pool all aliquots of the retrieved BAL ï¬uid for routine analyses (including the ï¬rst retrieved aliquot). 4. BAL cell differential counts with greater than 15% lym-
So when a continent meets a continent, no subduction occurs (instead, the plates collide and thicken). True subduction happens only to oceanic lithosphere. When oceanic lithosphere meets continental lithosphere, the continent always stays on top while the oceanic plate subducts.
The Process of Subduction. The process by which ocean floor sinks beneath a deep-ocean trench and back into the mantle is called subduction (sub duk shun) . As subduction occurs, crust closer to a mid-ocean ridge moves away from the ridge and toward a deep-ocean trench. Sea-floor spreading and subduction work together.