What most likely happened in sediment layer 5

 The correct answer is :  Probably a massive dust cloud formed, which caused a global cooling and lack of sunlight. As a result of this there were no plants of any kind and a mass extinction arose. Sedimentary rocks contain internal layers called stratification, which can vary, being some very thick and others too thin as millimeters.

gold discovery in california, and pioneer settlers were sometimes pulled west because they wanted to make a better living. others received letters from friends or family members who had moved west. these letters often told about a good life on the frontier. the biggest factor that pulled pioneers west was the opportunity to buy land.

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