Why is protected water usually safer to drink than unprotected water from wells or rivers

How does the bare soil surface type affect the amount of runoff

The creation of the trans-siberian railway allowed people to travel across russia. how could this railway impact russian culture?

When volcanoes erupt, magma (hot, molten rock) rises toward the surface of the earth. as magma cools, solid rock forms. this rock contains substances from the interior of the earth. which of the following natural resources is likely to be plentiful near subduction zones where volcanic activity has occurred in the past?