How fast do mountains grow?

The rate at which mountains grow can vary significantly based on several factors such as the type of mountain, the composition of the surrounding rocks, the geologic processes involved, and the erosional forces acting on the mountains. Generally, mountains are formed over long timescales, and their growth can be measured in millimeters to centimeters per year or even longer.

1. Orogenic Mountains (Continental Collision and Subduction Zones):

Orogenic mountains, such as the Himalayas and the Andes, form when continental plates collide or when an oceanic plate subducts beneath another tectonic plate. The growth of these mountains is a complex process involving crustal thickening, uplift, and erosion. They typically rise at rates ranging from a few millimeters to several centimeters per year, but these rates can vary depending on the specific region.

2. Volcanic Mountains:

Volcanic mountains, formed by the accumulation of lava and volcanic materials, can grow rapidly during eruptions. The growth rate depends on the volume and frequency of volcanic activity. The rate of growth for volcanic mountains can range from a few meters per day during an eruption to gradual growth over years and decades between eruptions.

3. Fault-Block Mountains (Horst and Graben Structures):

Fault-block mountains are formed when large blocks of the Earth's crust are uplifted or dropped along fault lines. The rate of growth for fault-block mountains can vary based on the activity and displacement along the faults. Uplift rates of several millimeters to centimeters per year have been observed in some regions with active faulting.

4. Salt Dome Mountains:

These mountains form when salt layers buried deep within the Earth rise due to their buoyancy and deform the surrounding rocks. Salt dome mountains can grow relatively rapidly, with uplift rates of several centimeters to decimeters per year. However, their growth is episodic and may be punctuated by periods of quiescence.

5. Uplift and Erosion:

In addition to the primary geological processes that contribute to mountain growth, the overall height and shape of mountains are also influenced by erosional forces, such as water, ice, and wind. Erosion can shape and modify mountains over time, leading to the lowering of peaks and the formation of valleys.

6. Long-Term versus Short-Term Rates:

It's important to note that the growth rates of mountains are generally measured over long geological timescales, often spanning millions of years. Short-term observations may not accurately capture the long-term growth rates, as mountain growth can be influenced by episodic events and variations in geologic activity.

Overall, mountain growth is a complex geologic process influenced by multiple factors, and the rates of growth can vary significantly depending on the type and location of the mountain.