Ocean ridge does not accompany volcanic activity in the Pacific Northwest.
<u>Explanation:</u>
In this process the denser oceanic plate force the thinner continental plate to sink into the mantle. This region is referred as subduction zone, where it results in intense volcanic eruptions and earthquakes.
The denser Pacific plate sinks because of the chunk pull impact and it likewise prompts the development of mountains. This sort of impact creates profound center seismic tremors.
It isn't related with the maritime edge as the mid-maritime edge shapes in a disparate plate limit. In the Pacific Northwest , the volcanic activity is carried out by the geological process majorly by subduction.
The youngest age of the shale is 910 ka. According to the principle of inclusions, the shale formed before the tephra, so the tephra must be younger than 910 ka.
