Are the Sierra Madre and Himalayas Fold Mountains?

Yes, both are fold mountains. Fold mountains form when tectonic plates collide, crumpling the crust into parallel ridges.

• Himalayas – Indian Plate colliding with Eurasian Plate; highest range (Everest 8,848 m), 2,400+ km long.
• Sierra Madre – North American Plate colliding with Pacific Plate (and subduction); includes Sierra Madre Occidental, Oriental, del Sur in Mexico; lower, fragmented into sub-ranges.

Both exhibit classic fold-mountain traits: sedimentary rock layers, steep flanks, linear ranges at convergent boundaries.