how well the flu vaccine is matched to flu viruses that are causing illness. Over a period of 31 seasons between 1976 and 2007, estimates of flu-associated deaths in the United States range from a low of about 3,000 to a high of about 49,000 people.
metamorphic rocks form from heat and pressure changing the original or parent rock into a completely new rock the parent rock can be either sedimentary igneous or even another metamorphic rock the word metamorphic comes from greek and means to change form the diagram above shows you how the rocks on earth have been changed continually over time from one rock type to another
Metamorphic Rocks. Metamorphic rocks are formed due to metamorphism from existing igneous or sedimentary rocks, or even from existing metamorphic rocks. When existing rocks undergo changes due to high pressure and/or high temperature and/or high shearing stresses, metamorphic rocks are formed. Igneous rocks are the oldest rocks, while metamorphic are being derivative of igneous rocks and sedimentary rocks. - Igneous rocks are the major proportion (nearly 95%) of the total rocks, while metamorphic rocks are found in a very small percentage.