4-ESS1 Earth's history in rocks and fossils
Aligned to 4-ESS1 — Next Generation Science Standards.
What this lesson teaches
Rocks are often stacked in layers, and the layers near the bottom were laid down first, so they are the oldest. Fossils trapped inside the layers are clues that tell scientists what plants, animals, and environments were like long, long ago.
Worked example
In the walls of the Grand Canyon you can see stripes of rock layers. The bottom layers formed millions of years before the top ones. A fish fossil found in a layer tells scientists that area was once underwater.
Practice questions
- In a stack of rock layers, which layer is usually oldest?
- What can a fossil tell scientists about the past?
- If you found a seashell fossil on a mountain, what might that mean?
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
4-ESS1 La historia de la Tierra en rocas y fósiles
Las rocas generalmente se apilan en capas, y las capas que están cerca del fondo se formaron primero, por lo que son las más antiguas. Los fósiles atrapados dentro de las capas son pistas que les dicen a los científicos cómo eran las plantas, los animales y los ambientes hace muchísimo tiempo.
Ejemplo: En las paredes del Gran Cañón puedes ver franjas de capas de roca. Las capas del fondo se formaron millones de años antes que las de arriba. Un fósil de pez encontrado en una capa les dice a los científicos que esa área alguna vez estuvo bajo el agua.
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