What improvement most dramatically increased the speed and lowered the expense of commerce in the first half of the nineteenth century?

answer: he got 23

explanation:

. west

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods