{Cover} CHIEF MOUNTAIN Special Bulletin No. 3 GLACIER NATURAL HISTORY ASSOCIATION Price 25 Cents By JAMES L. DYSON Head, Department of Geology and Geography Lafayette College [1] Until recently a geologist was visualized by most people as a queer sort of fellow who went around the countryside breaking rocks with a little hammer. Fortunately, the general public today has a much clearer picture of the geologist and his science, but there are still many among us who mistakenly feel that geology is

The most striking feature of the mountains—certainly the one which comes first to a visitor’s attention—is the color banding. No matter where one looks this feature greets his view. If he enters the park at the St. Mary Entrance, there ahead on the sides of Singleshot and East Flattop Mountains are white and purple bands. Should he enter first the Swiftcurrent Valley, he would soon note the banding in the mountains lying to his right and left, and finally culminating in the precipitous Garden Wa

This is the oldest of the several formations and thus occupies a stratigraphic position at the base of the entire series. It is composed mainly of sandy dolomites (magnesian limestones) and limestones which weather to a light buff color. It outcrops all along the base of the eastern front of the Lewis Range and comprises the entire block of Chief Mountain. Because of its comparatively great resistance to weathering and erosion it usually forms a conspicuous ridge or terrace wherever it crosses a

Lying on top of the Altyn are 3,000 or more feet of prevailing greenish shales and argillites [2] comprising the Appekunny formation. Slabs of these rocks, because of their great hardness, have been used as flagstones in the walks at the Many Glacier Ranger Station and adjacent Park Service residential area. Mud cracks and ripple marks are common. The formation is prominent on the side of Singleshot Mountain near the St. Mary entrance to the park, and everywhere immediately overlying the lighter

Because of their dominantly red color, the shaly argillites which comprise the bulk of this formation are the most conspicuous rocks in the park. They lie immediately on top of the Appekunny and although their thickness varies considerably it is greater than 3,000 feet in several localities. Interbedded with the red argillites are thin white layers of quartzite, a former sandstone which has been converted by pressure into an extraordinarily hard, dense rock. Mud cracks, ripple and current marks,

Next above the Grinnell is a thick limestone formation which, because of its weathered buff color, stands out in sharp contrast to the red beds upon which it rests. It is the greatest cliff-maker in the park and in several places its entire thickness of 4,000 feet may be exposed in a single nearly vertical cliff. Since it is younger than the three preceding formations, it is confined mainly to the higher elevations, capping many of the loftiest peaks within the Lewis and Livingstone Ranges. In t

Several hundred feet of limy beds which weather yellow-brown lie on top of the Siyeh. Although named for outcrops on the cliff above Shepard Glacier (south of Stoney Indian Pass and near the site of the old Fifty-Mountain tent camp) the formation is exposed on the summit of Swiftcurrent Mountain at the head of Swiftcurrent Valley, on Reynolds and Clements Mountains near Logan Pass, and on Citadel and Almost-a-Dog, visible from Going-to-the-Sun Highway in St. Mary Valley. The formation is replete

These beds have the same bright red color as those of the Grinnell. However, because they are the youngest rocks of the Belt series they outcrop only on a few mountaintops, and inasmuch as these are mainly in the northwest part of the park, comparatively few people have noticed this formation. Visitors to Cameron Lake in Waterton Lakes National Park can see it in the red north wall of Mount Custer. The mountains around colorful Boulder Pass and Hole-in-the-Wall Basin are likewise composed of it.

Soon after the youngest layers of Siyeh limestone had accumulated on the floor of the sea and while they were still under water, a mass of molten rock was squeezed up from far below and extruded in the form of a submarine lava flow over the recently accumulated sediments. Several times this lava poured out forming a total thickness varying between 50 and 275 feet. One of the best exposures is on the west side of Swiftcurrent Pass and in Granite Park just west and northwest of the chalet. In fact

Few persons visit the park without noticing the pronounced black layer, within the Siyeh formation, present on many of the high peaks. It is most in evidence on the face of the Garden Wall viewed from the vicinity of Many Glacier Hotel, although it is plainly visible also in Mount Wilbur and the wall above Iceberg Lake. Passengers on the Waterton Lake launch can see it cutting across the stupendous north face of Mount Cleveland. From Going-to-the-Sun Highway it can be seen on Mahtotopa, Little C

Not until the Cretaceous period of Earth history, about 100 million years ago, did the geologic record again become clear. At that time a great thickness of mud and sand was deposited in the geosyncline burying deeply the ancient Belt and other rocks which had accumulated as sediment during the preceding several hundred million years. Life had made tremendous advances in this interval, and the abundance of fossils in Cretaceous rocks indicates that the sea swarmed with shelled creatures during t

Toward the end of Cretaceous time tremendous crustal forces, principally from the west, were directed against the geosyncline with the result that its rocks were compressed and uplifted, converting the site of the former sea into a mountainous region. Similar activity took place throughout the length and breadth of the entire geosyncline, which resulted in the formation of the Rocky Mountain system stretching between Mexico and Alaska. A number of mountains were formed on other continents during

In Miocene and Pliocene time the mountains were deeply eroded by streams. It was during this time that Chief Mountain, Divide Peak, and two smaller outliers, and the fenster along Debris Creek were formed. All of the existing mountain valleys were cut out of the overthrust block, although not to as great a depth as they have today. The time required for their formation amounted to several millions of years. The result of all this erosion was a landscape very similar to the present day Blue Ridge

Although events of the last 9,000 or so years didn’t create the large spectacular features of the landscape, this period is nonetheless interesting because it witnessed the birth of all existing park glaciers and the return of the trees composing the present-day forests. As soon as the glaciers began to shrink trees undoubtedly started to reclothe the newly exposed surfaces. New varieties came from areas which had not been glaciated. From the Pacific coast came grand fir, Douglas fir, larch, hem

We know that the processes of erosion and weathering will continue, that alluvial fans and talus cones will grow larger, and gorges will be eroded deeper, and as a result the mountains will be cut down to lower elevations. But, as we have seen, this event will require much time. If the present climate continues for a few more years our remaining glaciers will disappear, but there is nothing in geologic history which says they won’t return again, possibly even to the size of their heyday in the P