Felsic lavas (dacites or rhyolites) tend to be highly viscous (not very fluid) and are erupted as domes or short, stubby flows. Viscous lavas tend to form stratovolcanoes or lava domes. Lassen Peak in California is an example of a volcano formed from felsic lava and is actually a large lava dome.
Most psychology degree courses want you to have a science related A level, so anything from biology, physics, chemistry, maths or psychology. I just finished a psychology degree and I didn't do biology at A level.
Most psychologists, on the other hand, have training at the doctoral level. Some specialties, like occupational industrial psychology require less, but it takes a doctoral degree to sit down and work one on one with clients as a clinical or counseling psychologist.