James L. Dyson

“ If you live in a place where man has covered up the rock and the soil evidence of geological processes is yielded by the buildings themselves, whether they be of stone quarried from the Earth’s crust, or of brick made from clay. The stone and brick are supported by a framework of steel originally taken from a mine in the form of iron ore. The concrete and asphalt of the roads came from rocks within the Earth, as did every drop of gasoline which plays so vital a part in world affairs today. ”

“ 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 something too remote for practical application. ”

“ Mud cracks, ripple and current marks, raindrop impressions, and other 8 features made while the sediments were accumulating are common. The red color is due to abundant iron oxide occurring mainly as a cement between the sand and mud grains. All the rocks of Glacier Park contain some iron, or rather contain iron-bearing minerals. These minerals have various colors unless they have been oxidized, in which case the color is red or brown. Oxidation of the Grinnell formation probably took place while the mud was accumulating and during those periods when it was exposed to the atmosphere. ”

“ Innumerable loose slabs of red rock along the side of the road contain excellent mud cracks and ripple marks. Near Avalanche creek on the west side of Logan Pass the highway crosses the Grinnell where it comes to the surface on the western limb of the big syncline.
The formation is well exposed in the vicinity of Sperry Chalet and Glacier. It forms all the mountains surrounding the basin in which the chalet is located, and the trail from chalet to glacier lies wholly on it. At the glacier intensely folded white quartzite layers and red argillites are very conspicuous. ”

“ 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. ”

“ But certain breeds of man are the only despoilers of mountains that we need fear, so if the good citizens of our land keep the human invader and his dams and earth-moving equipment out of our national parks these grand mountains will endure for many thousands, yes, even millions of years. ”

“ These younger layers are Cretaceous shales and sandstones underlying the plains immediately east of the mountains. The mountains themselves have been carved by streams and glaciers from the Belt formations comprising the upper block of older rock, that slice of the crust which has been moved more than 15 miles toward the east. The surface over which it was pushed is the Lewis overthrust. At the time this great break occurred the part of it now exposed in Glacier National Park was deeply buried. ”

“ 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 24 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 Pleistocene. ”

“ Dyson worked as a ranger-naturalist in Glacier National Park for eight summers starting in 1935.
[2] Argillite is the term used by geologists for a rock, originally a shale, which has been recrystallized or made harder by greater pressure. In external appearance it looks like shale.
[3] A dike is like a sill in all respects except that it cuts across adjacent layers instead of paralleling them.
[4] For a complete discussion of glaciers and their effects see Special Bulletin No. 2 (Glaciers and Glaciation in Glacier National Park) of the Glacier Natural History Association. ”

“ Thus, from here it is a short step to the realization that a number of geologic processes and agents working over long periods of time have given rise to innumerable features and structures ranging from the loftiest mountains down to the smallest hills and valleys; from the soil which grows our food to the gasoline and coal which feed our industries ”

“ A few species, among which are the alpine willows, driven southward from the far north during the Pleistocene period still persist at high altitudes but they are always ready to move down into the valleys if the 21 climate should again become cool. Of course, continued warming would cause them to disappear. After the large Pleistocene streams of ice disappeared there followed a period of about 5,000 years during which the climate was somewhat warmer and drier than at present, conditions under which even very small glaciers could not have survived. ”

“ The algae colonies are in the form of rounded masses up to several feet in diameter and bear a crude resemblance externally and internally to a head of lettuce or cabbage. Geologists know these algae by the genus name Collenia. Because of the rounded and smoothed surfaces on these colonies, mountain climbers frequently find the reef difficult to cross. ”

“ In most places these rocks are covered by glacial moraine, but they are exposed along the highway from Babb into the Swiftcurrent Valley, especially along the shore of Sherburne Reservoir and near the entrance station. Because these shales readily disintegrate when exposed to the atmosphere they give rise to slumps and landslides which, although of small proportions, cause a great deal of damage to the highway, sections of which must be rebuilt annually. At most damaged spots along the route the shales appear as a dark mud or clay in the roadcuts. ”

“ The answers to these and other questions come out as the geologic story unfolds. The American people are interested in this story for they realize that to understand what they see is to increase their enjoyment thousandfold. ”

“ Within the rocks of this formation there is a great abundance of small cubes believed to be casts of salt crystals which formed when the sediments were accumulating. Their presence indicates an arid climate and intensive evaporation of the sea, similar to the condition at Great Salt Lake today. ”

“ After the Pleistocene glaciers began their final retreat several thousand years elapsed before they disappeared from the mountains.
FRONT OF LEWIS RANGE, NORTH SIDE OF SWIFTCURRENT VALLEY. THE LEWIS OVERTHRUST LIES AT THE BASE OF THE CLIFF. THREE LARGE TALUS CONES ARE VISIBLE BELOW MT. ALTYN ON THE LEFT. (DYSON PHOTO)
One of the most conspicuous of all post-glacial features is the talus cone, an accumulation of angular rock fragments which fall from cliffs. ”

“ To inspect it, one need walk only about 200 yards along the trail leading to Granite Park. In a distance of less than 100 feet the trail traverses from fresh Siyeh limestone across the entire altered (contact-metamorphosed) zone, here 12 to 20 feet wide, into the center of the sill. All parts of the sill and adjacent rocks can readily be examined and studied in detail at this site.
TOP OF THE DIORITE SILL OF BLACKFOOT GLACIER. THE MAN IS STANDING ON THE SILL. LIGHT ROCK OVERLYING SILL IS CONTACT-METAMORPHOSED SIYEH LIMESTONE. (DYSON PHOTO) ”

“ The best known of these is Chief Mountain situated near the northeast corner of the park several miles west of the Chief Mountain International Highway. It is a mass of Altyn limestone rising vertically on its east, south and north sides for a distance of 1,500 feet. The Lewis overthrust is well exposed all around its base. ”

“ 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. ”