What can cause a gap in the rock record    a. erosion b. lack of rock deposition c. both erosion and lack of rock deposition d. neither erosion nor lack of rock deposition

What are economic systems and how do they differ?

Which of these was an accomplishment of the han dynasty? the invention of the seismograph finding a water passage to europe the invention of the ballpoint pen the invention of the abacus

What affected the second industrial revolution have on transportation