A surgical mask is used inside the operating room or during other sterile procedure areas to protect the patient environment from contamination. Surgical masks have ties so that they can be adjusted for fit, and are tied over the top of a surgical or bouffant cap.
rockfall. 1  an act or instance of the falling of rock, as in a cave-in or an avalanche. 2  a mass of rocks that have fallen: to be trapped under a rockfall.
force is often strong enough to split the rock. This process, called root wedging, is a kind of physical weathering (Figure 11.7). However, roots also produce enzymes that attack rock minerals. So root wedging is really a combination of physical and chemical weathering. Rockfalls Falling rock can break into very small pieces when it hits the ground. The graphic below shows an example of rocks (and trees!) affected by falling rock. Rockfalls can occur when a big chunk of rock is split off of a large landform by frost wedging or root wedging. Rockfalls speed up the weathering process by quickly