Description of a horizontal tunnel driven through a cold, steeply sloping glacier, altitude 14,000 feet (4267 m.) on Monte Rosa, from its surface right through to bedrock, a distance of 302 feet (42 m.). Temperatures found deep within this cold glacier were 18° F. (−7.78° C.) compared with 8° F. (−13.33° C.) near its surface, and again near contact with its rock bed. This internal heat is interpreted as heat supplied from the interior of the earth, and as indicative of existence of ice at pressure-melting-point in all cold ice glaciers, if thickness of ice is sufficient. Existence of such an underlay of ice at pressure-melting-point, varying in distribution with varying supply of internal heat, is shown to explain (1) cirque erosion, (2) uniform elevation of cirques in any one region, (3) existence of extrusion flow under certain conditions, and (4) control of cycles of continental glaciation, under extreme limits.