Explain the cause of salt water getting into the groundwater aquifers near the beach sections of this area of the world. ok this question is fr so i need 2-5 sentences

How would i answer this for an exam?

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons

Which are evidence of the seafloor spreading? a. molten material b. magnetic stripes c. continental material d. drilled core samples e. ocean water samples