Why did the development of time zones make train schedules more reliable?

Why did jefferson make the louisiana purchase?

Marine exptoration of oil uses seismic waves to locate oil in the seabed. what is a negative impact from seismic waves on the aquatic ecosystem of the ocean? a.seismic waves kill microoganisms b.seismic waves disrupts the sand and causes seafloor erosion c.seismic waves have virtually no adverse affects on marine life d.seismic waves damage the sonar that dolphins and whales use to orient themselves underwater

The "nationalists" and fascists battled against the "republicans" and communists in a civil war in the 1930s in