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 are formed by the alteration of pre-existing rocks from exposure to heat and pressure while remaining in a solid form. Metamorphism occurs by breaking bonds between atoms in a mineral so that the atoms rearrange themselves into new, more stable, mineral forms.here the pressure is not directed, nonfoliated metamorphic rocks are formed and lack the banding of minerals typical of foliated rocks. Figure 14.20 Quartzite is a nonfoliated metamorphic rock formed from sandstone, a sedimentary rock. Table 14.2 Common Metamorphic Rocks. Rock.