What period did the earliest amphibians appear?

Which set of characteristics best describes sedimentary rock? a) largest type of rock, made of organic matter, hardest type of rock b) often contains layers, forms near sources of water, contains fossils c) least abundant type of rock, made of other rocks, made mostly of minerals d) most abundant type in earth's crust, made of magma/lava, contains no fossils

Based on the topographic map of mt. st. helens, what is the contour interval of the volcano about height is 2,950 m?

What is true of sea slugs in these orders