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The Flume is located one mile northeast of the Whiteface Ski Center. It is a deep gorge cut by the river along the Wilmington Notch fault. The gorge can be seen by following the trail downstream on the right.
Parking N 44° 21.984 W 073° 50.465
*To get CREDIT for this cache and to demonstrate the educational value of your visit please E-mail the answers to the following questions. FINDS which do not meet logging requirements will be auto-deleted.
1. Notice the high rock walls of the Flume. What do you think caused these high rock walls?
Go to N 44° 21.983 W 073° 50.421
2. Standing at that location and based on what you have read above what type of rock do you think is on the side of the waterfall? What features led you to that conclusion?
3. Again standing at the above coordinates you will see numerous potholes. Do you feel these will get any deeper and if so why or why not?
The West Branch of the Ausable River emerges from Lake Placid and pursues a winding course for a number of miles through a broad valley and then suddenly enters the notch. In the midst of the notch the river becomes a raging torrent. The narrowness of the forge, the rock walls rising to staggering heights, and the rush and roar of the river at the bottom combine to make this one of the most romantic places of the Empire State.
After the river plunges of the picturesque High Falls it cascades and foams through this narrow gorge known as the Flume with it's high rock walls. By the slow scouring action of the flowing ice during the Ice Age this deep narrow gorge was cut.
An important fact is the existence of an old "fault" or fracture zone which can be traced through the notch and along the river course on either side of it for some distance. Sliping and shearing of the rocks along this fault have caused them to be crushed and broken, thus rendering them much easier prey to the action of weathering and erosion by both stream and ice.
Since the Ice Age the river has scoured out and very appreciably deepened the northern half of the notch. The work of down-cutting has taken place extra rapidly in the Flume because the stream follows part of the belt of highly fractured rocks along the fault.
The Conservationist
Volume IV July, 1921 Number 7
The term anorthosite, is applied to a rock that contains 90% or more plagioclase feldspar, with most of the balance usually pyroxene. With increasing pyroxene content, anorthosite grades into gabbro, while intermediate types are termed gabbroic anorthosite and anorthositic gabbro. The Adirondack Anorthosite underlies a large part of the Highlands Adirondacks. It includes a wide variety of rock types dominated by and all closely related in origin to true anorthosite. According to current belief, this huge body of anorthosite orginated as an igneous intrusion at great depth within the Earth's crust, either before or during the Grenville metamorhism which effected the entire region about 1100 million years ago. Strickly speaking, therefore, the rock should be called meta-anorthosite, since it is an igneous rock that has been metamorphosed.
The Adirondack Anorthosite contain two principle rock types, called Marcy-type and Whiteface-type. The Marcy-type may be considered to be the main body, called the Marcy Massif. The rock is generally massive (unlayered) and very coarse-grained (two-foot long, plagioclase crystals have been found, although they are rarely this large). The texture is most often prophyroclastic, that is, like an igneous porphyry with large crystals in a finer matrix, but produced by the incomplete grinding up of a coarser-grained rock during metamorphism. The Whiteface-type, by contrast, typically lacks porphyroclastic texture, and is generally finer grained, strongly foliated or layered, and more gabbroic (darker) than the Marcy-type. The Whiteface-type occurs primarily as a border facies. These rocks and other varieties may best be observed at the Flume roadcut and on Whiteface Mountain.
The Marcy Massif is believed to be a sheet-like body about three miles thick that had intruded in liquid form along two "roots" which extend downward at least 6 miles. Recent studies indicate that the tabular mass must originally have formed at a depth of 6-15 miles (in the deep core of the Ancestral Adirondacks) where temperatures as high as 1100° C and extreme pressures would have been sufficient to account for the mineralogy now present in the rock. The rock, therefore, is truly a messenger from inner recesses of the Earth. Its exposure at the surface signifies the removal of several miles of cover rock by erosion.
There is an 800-foot-long roadcut that provides a remarkable display of the rock types collectively termed Adirondack Anorthosite. You can see the course texture of the Marcy-type, and the even-grained, strongly foliated character of the Whiteface type. Another type, called the Type III, is an even- grained variety with peculiar pinkish to greenish plagioclase is the rock that makes up the walls of the Flume. Two small plugs of pegmatoid (very coarse-grained) anorthositic gabbro and anorthosite can be seen. The contact relationships between the Whiteface-type and Type III are of special interest. About 400 feet down the roadcut the Whiteface-type encloses Type III while at about 600 feet the reverse is true. This implies opposite age relationships in the two localities.
The cut is shot through with several nearly vertical, diabase dikes similar to those of High Falls gorge and up to six-feet thick. They are nearly parallel to the face, hence the irregular outline. Try viewing one of these down-strike, that is parallel to its boundary with the anorthosite, and you will see that its shape is truly tabular as a dike would be expected to be. It is significant that the orientation of the dikes is nearly at right angles to the foliation in the White-face type anorthosite, therefore the trend of the dikes is not influenced by the foliation. They also roughly follow the course of the river in the Flume, as do numerous shear or joint surfaces at the northern end of the cut. These fractures appear to control the river course for several miles upstream.
Rivers extend themselves by eroding headward and when they meet a mass of harder rock, falls are formed. Since the rate of erosion under falls is greater than elsewhere, the falls may be viewed as Nature's response to an obstacle placed in its path. In other words, the falls are an attempt by Nature to restore a condition of equilibrium represented by a smooth stream gradient without precipices.
The rushing water has produced numerous potholes in the hard bedrock of the streambed, some of them of very large size. They are very common in rushing mountain streams. The potholes are formed when swirling eddies cause sand, gravel, and even boulders to grind against the bedrock during an extended period of time. A pothole may have formed over 10,000 years ago more or less by glacial meltwaters.
Rocks and Routes of the North Country New York
Bradford B. VanDiver, Ph.D.
W. H. Humphrey Press In.
Geneva, New York 14456
We hope you enjoy your visit to the Flume!
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