The remains of eroded highland in desert and semi-desert environments are commonly called

1. Analyze the question The question asks for the name of the isolated remnants of highland left behind after long-term erosion in desert and semi-desert areas.

2. Explain the concept In arid and semi-arid regions, weathering and erosion (by wind, occasional flash floods and sheet wash) wear down highlands over a long time. Resistant rock survives while the surrounding land is lowered, leaving isolated, steep-sided hills standing above a flat plain. These are called inselbergs (German for "island mountains"). They are also known as bornhardts when they are dome-shaped.

Nigerian examples include Kufena Rock in Zaria, Zuma Rock near Abuja (often cited as an inselberg-type feature), and the Olumo Rock in Abeokuta.

3. Check each option

• A. Seif dunes: These are long, narrow sand dunes lying parallel to the wind direction. They are depositional features, not eroded highlands.
• B. Barchans: These are crescent-shaped sand dunes formed by wind deposition. They are also depositional features. (The question spells it "barchains".)
• C. Inselbergs: These are isolated residual hills left after the surrounding highland has been eroded. This matches the question.
• D. Volcanic plug: This is solidified magma in a volcano's vent, exposed after the softer surrounding cone is eroded. It is related to volcanic activity, not the general remains of eroded highland in deserts.

4. Answer The correct option is **C.

5. Exam tip Remember: "Insel" = island. Inselbergs look like islands standing in a sea of flat desert. Also remember that dunes (seif, barchan) are made of deposited sand, while inselbergs are left-over rock from erosion.