– A lunar eclipse can occur when part or all of the moon’s cross-section is covered by Earth’s shadow. It can happen when the sun, moon, and earth lie – A solar eclipse is a natural phenomenon that occurs every 25 years. An eclipse is a natural event caused by the shadow formed by the earth or moon – Besides human interference, species endangerment and extinction can happen without human interference. Extinction is a natural part of evolution. Fossil records show that long before people came – Coal is a fossil fuel created from the remains of plants that lived and died about 100 to 400 million years ago when parts of the earth – A natural stream of fresh water flowing downhill from its source in the mountains to meet an ocean or a lake is known as a river. The river – Landslides happen when dirt, rock, or mud suddenly fails or slides down a slope. Mudslides are the most common type of landslides. Thousands of landslides happen