Building Landforms Over Time
Aligned to HS-ESS2-1 — Next Generation Science Standards.
What this lesson teaches
Landforms result from a tug-of-war between internal processes that build up the crust and surface processes that wear it down. These act on very different scales: a mountain rises over millions of years, but a flash flood can reshape a canyon in hours.
Worked examples
Example 1
The Himalayas rise a few millimeters each year as India collides with Asia, a slow internal process. Meanwhile, rivers and glaciers carve valleys into them far faster, so the peaks we see reflect the balance between uplift and erosion.
Example 2
The Appalachians were once Himalayan in height. Erosion won because uplift stopped, and 300 million years did the rest.
Example 3
Uplift and erosion are a race, not a sequence. A mountain's height is the score at this moment, not a finished result.
Practice questions
- Observe: Some landforms take millions of years to form while others change in a single storm. What does that range in timescale tell you about the processes involved?
- Model: Draw a mountain and label one internal process building it up and one surface process wearing it down.
- Explain: A mountain range stops rising but erosion continues. Predict how its shape changes over the next million years and explain why.
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
Formación del relieve en el tiempo
El relieve resulta de un forcejeo entre procesos internos que levantan la corteza y procesos superficiales que la desgastan. Actúan a escalas muy distintas: una montaña se eleva a lo largo de millones de años, pero una inundación repentina puede remodelar un cañón en horas.
Ejemplo 1: El Himalaya se eleva unos milímetros cada año a medida que India choca con Asia, un proceso interno lento. Mientras tanto, los ríos y glaciares tallan valles mucho más rápido, así que los picos que vemos reflejan el equilibrio entre el levantamiento y la erosión.
Ejemplo 2: Los Apalaches alguna vez tuvieron altura himalaya. La erosión ganó porque el levantamiento se detuvo, y 300 millones de años hicieron el resto.
Ejemplo 3: El levantamiento y la erosión son una carrera, no una secuencia. La altura de una montaña es el marcador de este momento, no un resultado terminado.
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