NATIONAL PARK SERVICE Fauna of the National Parks of the United States No. 3 Birds and Mammals of Mount McKinley National Park

GEOLOGY OF THE MOUNT McKINLEY REGION

NUMEROUS inquiries regarding the supposedly volcanic origin of Mount McKinley have come to my attention and I am led, therefore, to quote the following data from Bulletin 687 of the United States Geological Survey, The Kantishna Region, Alaska by Stephen R. Capps. On page 22 of this bulletin the following statement appears:

Although the outermost range of foothills is composed dominantly of altered igneous rocks, the other foothill ranges and the main Alaska Range south of this region may he said to be composed primarily of material of sedimentary origin, with which are associated minor amounts of igneous material. The range is therefore the result of the folding and uplift of old sediments rather than a mountain mass formed by the injection of large quantities of molten intrusive rocks or by the upbuilding of a great mass of volcanic flows.

On page 71 of the same bulletin, when speaking of the origin of Mount McKinley, the author says:

An important geologic event that occurred during the closing stages of the Mesozoic era or at the beginning of the Tertiary period was the uplift of a part of the Alaska Range, probably along its present axis. This movement was the first of a series of uplifts, that by their combined movements have given rise to the range that now contains the loftiest peak on the continent, Mount McKinley.

Figure 1.—Map of Mount McKinley National Park.
(click on figure for an enlargement in a new window)