Wednesday, January 29, 2014

Adirondack Geology: The World Of Talus Slopes

talus screeGeological forces over millions of years coupled with the action of glaciers and weather have created massive piles of boulders at the base of towering rock walls and steep slopes in numerous locations throughout the Adirondacks.

Some of the more prominent accumulation of talus, sometimes called scree by climbers, occurs around Chapel Pond, throughout the Wilmington Notch, in the Cascades, around portions of Bald Mountain near Old Forge, and in many places near the shores of Lake Champlain. Talus is also present along the edges of some sections of rivers and larger streams that cut through substantial deposits of bedrock.

The very random placement of fallen boulders, slabs of rock and massive pieces of stone creates an abundance of small caverns, nooks, cubbies, and grottos connected by a labyrinth of narrow passageways, chimneys and tunnels. In shady places, such as in ravines, on north-facing slopes, and along the edges of streams and rivers, a carpet of moss frequently covers the surface of these piles of rock. In heavily forested settings, a layer of organic debris may develop in cracks and crevices that promotes the growth of some species of ferns, herbaceous plants and small shrubs.

The depth of this layer of talus can vary greatly from one location to another, however, many extend far enough down to get below the frost line, even during extremely frigid winters without much snow, such as the one our region is experiencing this year. In contrast, even during the height of a summer heat wave, the chambers and interconnecting passageways remain cool and moist. The absence of thermal extremes and a consistently high humidity deep within the recesses of a boulder garden make this type of setting an ideal retreat for numerous bugs and other invertebrates.

One mammal believed by naturalists to reign supreme in a talus environment is the long-tailed shrew, (Sorex dispar) which is ideally adapted for preying on the bugs that temporarily or permanently reside in this unique setting. While all species of shrews have a pointed, wedge-shaped snout, the nose of the long-tailed shrew is even more pointed, which allows this miniature creature to stick its nose into the very tight crevices used by many invertebrates as a winter retreat, or for the placement of their eggs at the end of their life cycle. Because the long-tailed shrew is able to find enough dormant spiders, centipedes, mosquitoes, and other insects during the cold months of the year in the hidden depths of the talus, it remains active throughout winter as do all species of shrews.

Another resident of talus slopes and places packed with loose rocks is the rock vole, (Microtus chrotorrhinus), which is also known as the yellow-nosed vole. Like several other species of voles, this mouse-size rodent strongly prefers to consume leaves and foliage of ground plants. It also ingests seeds and berries, but it seems to favor greenery over fruits. In the Adirondacks, several short stature plants retain their leaves in winter, which allows them to conduct photosynthesis in spring as soon as the air warms and liquid water becomes available in the soil. Bunchberry, spinulose wood fern, polypody fern, numerous members of the heath family and mosses all remain green throughout the year, and some of these plants are believed to serve as a source of food to the rock vole as it periodically ventures to the surface to nibble on vegetation. Like the long-tailed shrew, the rock vole also remains active throughout the winter, indicating that it is able to find enough greenery and seeds to maintain a state of good health during this time of year.

Talus slopes and boulder laden areas, especially in moist settings near water, create a unique environment of which very little is known. Because of the difficulty in accessing the recesses of the small chambers and caverns well below the surface of the ground, or dozens of feet horizontally into a hillside, few researchers have ever attempted to gain information on the conditions and residents of this community. It is believed that both the long-tailed shrew and rock vole are both abundant and fairly wide spread throughout the Park, yet virtually nothing is known of the life history of either of these mammals. Scientists are also unsure of any interaction that may occur between them, and the impact that they have on their surroundings.

I find it interesting that much is known about cougars and wolves, which, for all practical purposes do not exist within the Park, yet the lives of two of the Park’s fairly common mammals remain a giant mystery. Basic questions, such as what kind of nest do theses animals build, do they store any food during the autumn, what type of social structure do they have, and what are the basic aspects of their breeding season have not been answered

The Adirondacks harbors many types of wildlife habitats. Some of these settings have been regularly studied, yet some remain almost completely unexplored. Talus slopes are quite widespread throughout the Park, and hold many basic secrets of nature here in the Adirondacks.


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Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

6 Responses

  1. Paul says:

    Tom I can’t tell you how many times my old earth science teacher (you know, and worked with him in SL) points out the Talus slope you pass not long before you get to the Northway on Rt. 73. This was a ritual each year on the way to Florida for spring break!

    My kids now can certainly identify a Talus slope. Whenever we pass there you will hear – “we know dad -Talus Slope”.

    Thanks for the article.

  2. Pete Nelson says:


    Perhaps you can help me with a long-term mystery. Something like twenty or thirty years ago I read an article about the Adirondacks that described the talus cave system in Indian Pass, with its unexplored passages and glacial ice. The article claimed that this cave system, the extent of which was unknown, might in fact be the largest talus cave system on Earth.

    I know that I am not inventing the article, but I have never been able to find such a reference again.

    Is there anything to this claim? Do you know the reference or any similar reference? Is the claim malarky?

    Thanks for all the informative articles.


  3. Bob Meyer says:

    Oh Pete! I want to know about this!

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