Denali's official 20,310-ft elevation was measured to the top of its ice cap.

Denali's official elevation of 20,310 ft is measured to the top of the summit ice cap — the highest surface a surveyor can actually stand on and observe. Surveyors estimated roughly 13.6 ft of ice beneath that measurement point, but could not definitively locate the rock summit underneath. The published figure is therefore an officially measured elevation of a specific surface, not a claim about the height of the underlying rock.

Officially measured — to the top of the summit ice cap; the rock summit beneath was not definitively located.

Measurement surface is the ice cap, not rock. Surveyors could not definitively locate the rock summit.

• 2015 Denali summit survey — National Park Service

• Measurement trap⛳42.67 mm isn’t “the diameter of a golf ball.”
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