Sable Lake Ice Update, First Wild Flowers, Dunes, and Beaver Information

Yesterday it rained most of the day. Late in the afternoon I went over to Sable Lake to check on the progress of the ice melting. The wind concentrate the ice toward the south and west part of the lake leaving the east side of the lake ice free. It is amazing how fast open water appeared.

A couple of days ago I hiked down the Masse Homestead/Logslide trail and went up into the dunes. Along the trail I saw the first wild flowers of the spring.

Soon the forest floor along this trail will be covered in wild flowers. It is almost as if the forest celebrates the coming of spring.

Up in the dunes I spotted this telegraph pole that has been split. I'm sure I've seen this pole before, but the weather over the fall or winter must have split it.

The last shot below shows two large trees that were cut down by beaver. These trees were more than 20 feet long and at least 12 inches in diameter. The beavers were bold, but not able to drag them away.

I have always been intrigued with beavers and decided to do a little bit of Internet research.

The beaver (genus Castor) is a primarily nocturnal, large, semi-aquatic rodent. Beavers are known for building dams, canals, and lodges (homes). They are the second-largest rodent in the world (after the capybara). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was once more than 60 million, but as of 1988 was 6–12 million. This population decline is due to extensive hunting for fur, for glands used as medicine and perfume, and because their harvesting of trees and flooding of waterways may interfere with other land uses.

Beavers are known for their natural trait of building dams on rivers and streams, and building their homes (known as "lodges") in the resulting pond. Beavers also build canals to float build materials that are difficult to haul over land. They use powerful front teeth to cut trees and other plants that they use both for building and for food. They usually drag and float the trees through the water. In the absence of existing ponds, beavers must construct dams before building their lodges. First they place vertical poles, and then fill between the poles with a crisscross of horizontally placed branches. They fill in the gaps between the branches with a combination of weeds, mud, and rocks until the dam impounds sufficient water to surround the lodge. The lodges are usually built near the dams. Each lodge has one nesting chamber located above the water’s surface and several entrances through underwater channels. Wonderful diggers, beavers may also burrow underground tunnels from the banks up to favorite feeding grounds and excavate channels to other parts of the stream or river.

Beavers live an average of 10 to 12 years in the wild. They generally mate for life and live in family units that consist of an adult male and female and three to four kits. Once they are old enough to leave the lodge, kits spend most of their time playing in the water around the lodge, but are buoyant and cannot dive. Young beavers usually stay with their parents—helping out with the family chores of maintaining the lodge and dam, until they reach sexual maturity at about two years of age. Then, chased away from their natal territory by their parents, they go stake their own claim usually downstream.

They are known for their alarm signal: when startled or frightened, a swimming beaver will rapidly dive while forcefully slapping the water with its broad tail, audible over great distances above and below water. This serves as a warning to beavers in the area. Once a beaver has sounded the alarm, nearby beavers will dive and may not reemerge for some time. Beavers are slow on land, but are good swimmers, and can stay under water for as long as 15 minutes.

Beavers are herbivores, and prefer the wood of quaking aspen, cottonwood, willow, alder, birch, maple and cherry trees. They also eat sedges, pondweed, and water lilies.

Beavers do not hibernate, but store sticks and logs in a pile in their ponds, eating the under bark. Some of the pile is generally above water and accumulates snow in the winter. This insulation of snow often keeps the water from freezing in and around the food pile, providing a location where beavers can breathe when outside their lodge.

Sable Lake Ice Melt

So how does ice melt on a frozen lake anyway?  I have never actually seen the final moments when the ice on the surface of Sable Lake in the Pictured Rocks National Lakeshore goes away.  I have been watching it over the last few days.  The ice is breaking into sections and getting darker in color. 

I decided to go onto the Internet to see if there is an explanation of how ice melts.  From various web pages, I have pieced together the following explanation.  To understand how a lake thaws, it's helpful to know how it freezes.

1. As water cools, it gets more dense. That's why colder water is at the bottom of a lake in the summer -- it is denser and sinks.  But when water cools to 39 degrees it gets as dense as it's going to get. As it gets colder still, water actually becomes less dense. So the coldest water remains on the surface of a lake and eventually starts to freeze.
2. Since ice is even less dense than water that is between 32 and 39 degrees, it floats on top.  That is why ice cubes float in a glass of water. If this were not true and if the colder water and ice sank to the bottom,  lakes would freeze solid from the bottom up.  This would not be good for fish, other aquatic animals, aquatic plants, and fishermen!
3. The lake loses heat to the atmosphere, and then on a day or night when the wind is not blowing, ice forms. Lakes tend to start freezing first along shorelines, where water is shallow and calm.  The ice starts forming and grows away from shore and gets thicker as long as the lake can continue to lose heat.
4. In most Januaries and Februaries, snow both reflects sunlight and insulates the lake. With a thick snow layer, the lake neither gains nor loses heat. The bottom sediment is actually heating the lake water slightly over the winter, from stored summer heat.
5. In the spring, the ice starts to melt in reverse order of how it formed.  Around March as the air warms and the sun gets more intense, the snow melts, allowing light to penetrate the ice. Because the ice acts like the glass in a greenhouse, the water beneath it begins to warm, and the ice begins to melt FROM THE BOTTOM. The shallow shorelines melt first, because those waters warm first. The water beneath the ice warms and pushes up against the bottom of the ice, eroding it.  Ice also melts from the surface, and rain can help the process. The ice loses its structural integrity as it warms. It's weakened by the heat it's absorbing.
6. When the ice thickness erodes to between 4 and 12 inches, it transforms into long vertical crystals called "candles." (See pictures taken from the Internet below.). These crystals that develop in columns perpendicular to the surface of the lake conduct light even better, so the ice starts to look black because it is not reflecting much sunlight.  Candle Ice makes a clinking sound when the candles are broken apart and floating in the water, bumping up against each other. The ice still might be 18 inches thick, but it won't support weight. It's soft and flexible -- ''rotten'' some say. That's why when the ice goes away in the spring, it's not a thin layer that goes out.  

1. Warming continues because the light energy is being transferred to the water below the ice. Melt water fills in between the crystals, which begin breaking apart. The surface appears grayish as the ice reflects a bit more light than before. Wind breaks up the deteriorating ice and speeds up the melting process. The lake turns into a big slurpy, with the ice crystals tinkling in the waves. Then it's just a matter of time before the ice disappears.  Usually this happens in a matter of hours.

The following series of shots show pictures taken from the overlook on the northeast side of Sable Lake.  I took similar shots 24 hours apart.  The first picture below was taken on April 24th and the next on April 25th.  Notice how the ice is much darker on the second day.

Another series:  day 1 and then day 2.

Here is a close up of some of the swirls from day 1.  I am not sure if these are left over from snowmobilers or if the swirls form from wind blown snow drifts.

From one day to the next, the amount of open water along shore at least doubled. 

This is a shot from the east end of the lake.  There is a lot of open water here, probably because of the shallow depth.  It looks like in some cases the ice is melting in sections.

We have had a couple of good sunsets in the past few days.  Here is one.

Sable River Hike

On Saturday, friends and I hiked from Sable Falls into the dunes and along the west side of Sable River, before we doubled back into the dunes. There was very little snow and ice left along the side of Sable River.

Along the path, I spotted this Striped Maple tree. I just love the bark on these young trees. Other information about this species:

Leaf: Opposite, simple, orbicular, 5 to 8 inches long, 3-lobed (resembles a goose foot), serrated margin; green above and paler below.

Flower: Dioecious; yellow-green, bell shaped, 1/4 inch long, appear in long, hanging slender clusters in late spring.

Fruit: Paired, wide-spreading samaras, 3/4 to 1 inch long, in hanging clusters, ripen in late summer and early fall.

Twig: Moderately stout, green changing to red or reddish brown, smooth; reddish buds narrowly ovoid, stalked, valvate.

Bark: When young, smooth gray-green with prominent white lengthwise stripes, older bark becomes reddish brown.

Form: Small tree or large shrub up to 30 feet tall.

The range for this tree is shown on the map below.

 As we walked along the river, we spotted this partially completed beaver dam.

We approached the bluff over looking Lake Superior just west of Sable River.  Here is a close up shot of part of the river's mouth, as well as a couple of shots of a guy who was fishing the river's mouth.



More shots from the bluff....



Now that all the beach ice has melted, agate hunters are showing up.

There is almost no snow left in the dunes at all.  Below you can see one small area of dampness with a bit of white snow showing in the top center part of the picture.



Hurricane River to Log Slide Hike

A whole group of us decided to take advantage of the beautiful weather a couple of days ago.  We used a couple of vehicles, leaving one at the Log Slide, and hiked east 3.5 miles from the Hurricane River.  On the shore at the east end of the campground lies a big piece of shipwreck.

The 1.5 mile trail to the lighthouse is actually the gated Coast Guard road.  It is flat and doesn't challenge you much for exercise, but it is a delightful walk.

The beach in front of the lighthouse is lined with Jacobsville sandstone.

Back in the mid-1800s, sailors dreaded the eighty miles of dark shoreline that stretched east from Grand Island Lighthouse near Munising to the light on Whitefish Point. Unmarked by any navigational light, these dangerous shores claimed dozens of ships. To fill the gap, a lighthouse was placed on Au Sable Point in 1874. An eighty-seven-foot brick tower was built on a rise, placing the light about 150 feet above Lake Superior's surface. The light tower's base diameter is 16 feet. A fog signal building was built in 1897.

The original two-story keepers dwelling was attached to the light tower in the back. In 1909, the building was added on to the front so it would accommodate two families. One lived upstairs, one down. The head keepers residence was built in 1909.

The Third-Order Fresnel Lens displayed a fixed white light. The attached, two-story brick keeper's dwelling was large, but those who lived in it knew theirs was one of the most remote mainland light stations in America. The nearest town, Grand Marais, was more than 12 miles away, and there was no road. Keepers either hiked in or came by boat.

The Coast Guard automated the light in 1958, later turning the property and buildings over to the National Park Service for inclusion in Pictured Rocks National Lakeshore.

Although the light remains active, the old Third Order Fresnel Lens has been removed from service and is in the lens room in the light tower. The lighthouse tower, the attached red brick keeper's house and the red brick fog building are still standing. The light is presently powered by solar power.

The billion year old Jacobsville sandstone serves as a platform for the waves and the ice to move large boulders toward shore.  This red and cream mottled sandstone is a half billion years older than the other sandstones in the Lakeshore.

After leaving the lighthouse and continuing east,  there is a two mile trail mostly uphill to the log slide.  We call it the hill that never ends.

Summer Lighthouse ToursAu Sable Light Station tours are scheduled Wednesday through Sunday from Memorial Day through Labor Day (as staffing permits). (No tours on Monday and Tuesday.) Tours begin at 11 a.m. and run through 5 p.m.

The 30-40 minute Park Ranger guided tours begin at the lighthouse east porch. Check with the volunteers at the Au Sable Maritime Museum for the next tour time. Tour fee is $3 for those 6 and older. Correct change is greatly appreciated.


Summer Transportation The Lakeshore has partnered with the Munising-based public transportation company Altran for van transportation to the light station on a limited number of Saturdays in 2011. Altran will transport people with mobility limitations on the hour for a $5 round trip fee ($2.50 one way).

The van will be available from 11 a.m. to 5 p.m. Visitors can meet the driver in the picnic area parking lot.

Once the van arrives at Au Sable, getting around the site is up to the individual. Visitors should be aware there are very sandy soils, narrow sidewalks, and only the boathouse is accessible on one floor. The other buildings require climbing steps

NOTE:  Some of the information for this posting came from http://www.exploringthenorth.com/ and the National Park Service web site.

Grand Sable Dunes Hike

We heard that H58 west was open, so we drove into the Pictured Rocks National Lakeshore and decided to hike the dunes on the Log Slide end.

The Grand Sable Dunes are some the world’s most pristine perched dunes. They cover a five mile stretch between the Sable River and Au Sable point. Glacial ice that melted within the Superior Basin around 10,000 years ago produced many large rivers. These rivers deposited millions of tons of debris into many different configurations south of the Superior Basin. The Grand Sable Banks most likely originated along one of these glacial rivers.

Around 8,500 years ago, the Pictured Rocks area then became very dry when the Lake Superior basin changed its drainage pattern and began emptying to the north from its east end when this new outlet was the low spot. A north facing bluff formed and remained in place for 4,500 years right around the Grand Marais area.

Between 4,000 and 6,000 years ago, the land mass that is now the Upper Peninsula started to rebound upward from the weight of the previous ice glacier. This is called isostatic rebound. The U.P. is still rebounding today. The land forming the lake's outlet at North Bay began to rise, which reduced the amount of outflow and caused water levels to rise rapidly. In fact, Lake Superior rose to about 40 feet higher than it is today! The rise in lake levels formed Lake Nipissing. Lake levels of Lake Nipissing also began to rise which caused the Grand Sable Banks to become unstable. The higher water eroded the bluffs which left them exposed to wind. A dominant northwesterly wind blew through the Grand Sable Banks which carried the wind from the bluff to the top of the flat upland. This sand was “perched” on top of the upland, hence the name, “perched dune system.”

The climate of the Grand Sable Dunes is typical of any Michigan climate. The winters are fairly long and cold while the summers are short and cool. The location of the dunes happens to be the second most cloudy area of the United States. The average cloud cover is approximately 70%. Grand Marais’ annual temperature is 40.8 degrees Fahrenheit with precipitation totaling 31 inches a year. During the winter season snowfall accumulation ranges from 130 to over 200 inches. Because the dunes are so close to Lake Superior extreme low temperatures in the winter and extreme high temperatures in the summer do not occur.

If you plan on taking the hike to the Grand Sable Dunes the best way to get there would be to take the trail that starts at the west end of the Sable Falls parking area. While on the trail you will walk through an old field and eventually cross over a bridge that runs about Sable Creek. For the next ¼ mile you will go through the forests and dune transition areas. Along the trail, stop and take a look at the wayside exhibits. Another way to access the dunes is through the north country trail while is located ¼ mile east of the log slide.

In the spring after the snow and ice melts, there are often these carved ridges that form along the dunes.  Over the course of the summer, the definition of these ridges decreases due to erosion and the dunes flatten out again.

Along the perimeter of the dunes as well as in areas throughout the dunes, there is a continuous "battle" between sand and trees. It appears that the forests are winning this battle. Scientists who are studying vegetation changes at the Grand Sable Dunes have found that there has been an increase in the number of jack pine forests throughout the past 100 years. Jack pine forests have multiplied at an astonishing rate. There has been a fivefold increase in forest cover within the last 50 years.

Although the forests are advancing, the strong winds do take their victims.  This fallen tree below serves as a host for a colony of shelf fungi.

I absolutely love the patterns of snow and sand that form in the spring.



I think I have shown this telegraph pole shot before, but I like the perspective it gives.



NOTE: Some of the information from this posting was acquired from http://www.geo.msu.edu/geogmich/grand_sable.htm and http://hunts-upguide.com/grand_marais_grand_sable_bank___dunes.html.