The Formation of Crater Lake and the Pinnacles

Mount Mazama's violent eruption and collapse resulted in Crater Lake's formation. The Pinnacles' darker ash and tephra at the top indicate more recent eruptions, while the lighter ash at the bottom signifies earlier activity.

The Formation of Crater Lake

Explanation: The reason that the Pinnacles, situated southeast of Crater Lake, present darker ash and tephra at the top and lighter-colored ash and tephra at the bottom can be attributed to the varying volcanic activity over time. Primarily, it's because of the different layers of ash and tephra that were deposited during successive eruptions.

Approximately 7,000 years ago, a substantial volcano, known as Mount Mazama, was present at the site of the modern-day Crater Lake. This volcano experienced a violent eruption, causing the top of it to collapse into a cone and form a caldera. Over time, water filled the caldera, leading to the formation of Crater Lake.

The subsequent eruptive activity of Mount Mazama and nearby volcanic entities, such as the one responsible for creating the Pinnacles, resulted in the deposition of different layers of ash and tephra. These layers would have different colors, largely due to the differing chemical compositions and temperatures of the eruptions. Therefore, the dark ash and tephra you see at the top represent the remnants of more recent eruptions, while the lighter ash and tephra at the bottom were from earlier periods of activity.