the eruption of mount vesuvius -lrb- vuh- soo - vee -us -rrb- in southern italy in a.d. 79 , for example , caught the people in the nearby city of pompeii -lrb- pom-pay -rrb- so much by surprise that many died where they stood , and the tons of ash and rock that covered the city preserved it for nearly 1,700 years , giving us our most accurate information about roman life of that time. ;