We know that dry and wet periods follow a cycle of 550 years because of a. people keeping records of rainfall.
tree ring analysis.
C. the study of fossils.
d the Spanish documenting it

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 ideas, institution, and causes became the focal points of chinese and islamic resistance respectively to the west in the latter half of 19th century and the first decades of the 20th

What was a northern objection to the kansas-nebraska act?