July 31, 2011
A small, rounded hill, knob, ridge, or mini mountain that rises abruptly from relatively flat surroundings. “Inselberg” is a loan word from German and literally means “island mountain.”
Originally, the term inselberg was used to apply to landforms in hot, arid regions; early German explorers were particularly impressed with the “island mountain” landforms which they observed in southern Africa. However, the term can also be applied to similar landforms in more humid regions.
Inselbergs are generally erosional remnants. Often, inselbergs are composed of harder igneous rock (such as granite) that is more resistant to erosion. However, inselbergs may also form in sedimentary rocks.
A variety of other terms, both scientific and colloquial, are also used to describe “island mountains.” Among these are monadnock (after Mt. Monadnock in my home state of New Hampshire), bornhardt (after the German geologist and explorer who coined the term “inselberg”), tor, butte, and monument. The distinctions between these various terms are somewhat confusing and not consistent in the scientific literature. Generally, more rounded landforms are described as inselbergs or monadnocks while flat-sided, towering landforms are described as monuments.
Whatever term or terms you use to describe geological island mountains or towers, these distinctive landforms are beautiful, intriguing, and can often provide information about current and past erosional environments. Island mountains and towers are also often very fun to climb or hike.
My favorite island mountain is called “Leeu Se Kop” or “Lion’s Head” and is located in my adopted home city of Cape Town, South Africa. Lion’s Head is a sedimentary erosional remnant that is composed of the same sandstone as nearby Table Mountain. Hiking to the top of Lion’s Head takes about an hour. At the top of Lion’s Head there are is a gorgeous 360-degree view: ocean on three sides and towering Table Mountain on the fourth side. A popular activity among Capetonians and visiting tourists is to hike up Lion’s Head just before sunset on a night with a full or almost full moon. On full moon nights, dozens of people hike up Lion’s Head to watch the sunset. While the sun sets, people relax at the top with picnic baskets and bottles of wine or beer. After the sun has set and the full moon has risen, everyone hikes back down the island mountain.
“inselberg, n.” The Oxford English Dictionary. 2nd ed. 1989. OED Online. Oxford University Press. 30 July 2011.
“monadnock, n.” The Oxford English Dictionary. 2nd ed. 1989. OED Online. Oxford University Press. 30 July 2011.