Aortic valve calcification is a condition in which calcium deposits form on the aortic valve in the heart. These deposits can cause narrowing at the opening of the aortic valve.This narrowing can become severe enough to reduce blood flow through the aortic valve, a condition called aortic valve stenosis.Aortic valve calcification may be an early sign that you have heart disease, even if you don't have any other heart disease symptoms.Calcification and stenosis generally affect people older than age 65. When it occurs in younger people, it's often caused by: 1  A heart defect that's present at birth.ortic valve calcification may be an early sign that you have heart disease, even if you don't have any other heart disease symptoms. Calcification and stenosis generally affect people older than age 65. When it occurs in younger people, it's often caused by:
Occasionally, however, masses of hotter-than-normal rock rise independently of the broad flow, like bubbles through a flowing stream. These masses of very hot rock form rising columns with rounded tops, called plumes.he rising hot rock comes in contact with cold rocks near the surface of Earth where it gives off its heat, cools, and sinks again. Most of the rock in the mantle moves in this broad cyclic flow, indicated by the arrows in the figure.
A hot, less-dense lower boundary layer sends plumes of hot material upwards, and likewise, cold material from the top moves downwards. Convection is the heat transfer due to bulk movement of molecules within fluids such as gases and liquids, including molten rock (rheid). Convection takes place through advection, diffusion or both. Convection cannot take place in most solids because neither bulk current flows nor significant diffusion of matter can take place. Diffusion of heat takes place in rigid solids, but that is called heat conduction. Convection, however, can take place in soft solids or mixtures where solid particles can move past each other.