August 31, 2015
Confession: I probably don’t give Silver Lake Dunes State Park enough love. What an incredible place.
In Scientific American Robert S. Anderson, associate professor of earth sciences at the University of California at Santa Cruz explains why regular, wavelike shapes form when the wind blows over the sand on the beach for a long time:
Ripples in sand, found on both beaches and dunes, are one of nature’s most ubiquitous and spectacular examples of self-organization. They do not result from some predetermined pattern in the wind that is somehow impressed on the surface, but rather from the dynamics of individual grains in motion across the surface. They arise whenever wind blows strongly enough over a sand surface to entrain grains into the wind. The subsequent hopping and leaping of these grains is called saltation. Saltating grains travel elongated, asymmetric trajectories: Rising relatively steeply off the bed, their path is then stretched downwind as they are accelerated by drag forces. They impact the sand surface centimeters to tens of centimeters downwind, typically at a low angle, around 10 degrees. It is this beam of wind-accelerated grains impacting the sand surface at a low angle that is responsible for ripples.
“An artificially flattened sand surface will not remain flat for long. (Try it on the beach or on the upwind side of a dune and see for yourself.) Small irregular mottles in the sand surface, perhaps a couple centimeters in wavelength, rapidly arise and grow once the wind starts to blow hard enough to initiate saltation. They then slowly organize themselves into more regular waves whose low crests are aligned perpendicular to the wind direction and begin to march slowly downwind. Typical ripple spacing is about 10 centimeters, whereas the typical height of the crests above the troughs is a few millimeters. The pattern is never perfect, but instead the ripple crests occasionally split or terminate, generating a pattern that looks remarkably like one’s fingerprint.
Read on for a whole lot more including Michigan Sea Grant educator Walt Hoagman explaining how the speed of wind (and water) over sand influences the waves.
August 19, 2015
The National Park Service has opened a formal public comment period that will close on August 29, 2015 regarding future management options for wolves in Isle Royale National Park. The wolf population has plummeted because of a lack of gene flow from the mainland and park management is considering an array of options. If you have commented before, do it again as anything preceding the current comment period is now considered informal input and won’t be considered further.
Moose have important effects on island vegetation, including forest cover, and wolves are the only moose predator on the island. The wolf population on Isle Royale is very low. With their long-term survival on the island in question, the moose population is likely to increase in the short term (5-10 years), which could result in impacts to vegetation and forest cover because of over-browsing.The six plan options they lay out in this PDF are:
- No-action alternative: Current management would continue; the park would not actively manage vegetation or the moose and wolf populations
- Introduce wolves once: Reestablish wolves on the island by bringing in new wolves one time to mimic a migration event; no moose management
- Maintain both species: Maintain populations of moose and wolves on the island, which could include wolf reintroduction or augmentation
- Introduce wolves once and reduce the moose population: Reestablish wolves on the island by bringing in new wolves one time; reduce moose density if/when the wolf population is no longer impacting the moose population and moose herbivory is having a demonstrated impact on park resources
- Reduce moose population: No wolf reintroduction or augmentation; reduce moose density if/when the wolf population is no longer impacting the moose population and moose herbivory is having a demonstrated impact on park resources
- Intensively manage the moose population: No wolf reintroduction or augmentation; intensively manage moose population to a low level; potential for direct vegetation restoration through seed gathering and planting on offshore islands
Click over for more and to comment.
The Wolf Moose Project on Isle Royale is the longest continuous study of any predator-prey system in the world. Rolf Peterson began leading the wolf moose project in the early 1970s, and remains a world authority on wolves and moose. About this photo he says:
It was a remote camera photo that I set up. It shows the alpha male in the Chippewa Harbor Pack in 2009, revisiting the remains of a moose the pack killed in the adjacent pond the previous autumn. The wolves managed to yank the remains out of the pond the next summer and consume the rotting carcass.
You can view this photo background bigtacular and follow the Wolves & Moose of Isle Royale on Facebook for updates.
More wolves on Michigan in Pictures.
August 10, 2015
The annual Perseid Meteor Shower peaks August 11-13 and is the closest thing to a sure thing in when you’re talking meteor showers. The Perseids kick out 10+ meteors per hour at peak, and the darker your setting, the more you will see. EarthSky has detailed tips & diagrams about this summer favorite in Everything you need to know: Perseid meteor shower:
Start watching in the second week of August, when the Delta Aquarid meteor shower is rambling along steadily, reliably producing meteors each night. Then keep watching in the second week of August, when the Perseids are rising to a peak. The Perseid shower is known to rise gradually to a peak, then fall off rapidly afterwards. In early August (and even through the peak nights), you’ll see them combine with meteors from the Delta Aquarid shower. Overall, the meteors will be increasing in number from early August onward, and better yet, the moonlight will diminish until the new moon on August 14, 2015.
Don’t rule out early evenings. As a general rule, the Perseid meteors tend to be few and far between at nightfall and early evening. Yet, if fortune smiles upon you, you could catch an earthgrazer – a looooong, slow, colorful meteor traveling horizontally across the evening sky. Earthgrazer meteors are rare but most exciting and memorable, if you happen to spot one. Perseid earthgrazers can only appear at early to mid-evening, when the radiant point of the shower is close to the horizon.
As evening deepens into late night, and the meteor shower radiant climbs higher in the sky, more and more Perseid meteors streak the nighttime. The meteors don’t really start to pick up steam until after midnight, and usually don’t bombard the sky most abundantly until the wee hours before dawn. You may see 50 or so meteors per hour in a dark sky.
An open sky is essential because these meteors fly across the sky in many different directions and in front of numerous constellations. If you trace the paths of the Perseid meteors backward, you’d find they come from a point in front of the constellation Perseus. But once again, you don’t need to know Perseus or any other constellation to watch this or any meteor shower.
Read on at EarthSky for lots more and I hope you get a chance to enjoy Michigan after dark this week – it’s worth it!!
View Ken’s August 2012 composite of 8 meteors taken over an hour at the Grand Traverse Lighthouse on Cathead Bay bigger, see more in his massive Skies Above slideshow and head over to Ken Scott Photography on Facebook for a Perseids photo from last night!
PS: You can see a timelapse clip from this night on YouTube too!
July 15, 2015
Anyone remember Hipstamatic? This is a shot of Pluto in Dave Kirby’s cool installation of the planets along the TART trail in Traverse City (created prior to the de-planetization of Pluto). I don’t usually feature my own photos here, but I had to find something to celebrate NASA’s historic 3,000,000,000 mile journey to Pluto:
After a decade-long journey through our solar system, New Horizons made its closest approach to Pluto Tuesday, about 7,750 miles above the surface — roughly the same distance from New York to Mumbai, India – making it the first-ever space mission to explore a world so far from Earth.
“I’m delighted at this latest accomplishment by NASA, another first that demonstrates once again how the United States leads the world in space,” said John Holdren, assistant to the President for Science and Technology and director of the White House Office of Science and Technology Policy. “New Horizons is the latest in a long line of scientific accomplishments at NASA, including multiple missions orbiting and exploring the surface of Mars in advance of human visits still to come; the remarkable Kepler mission to identify Earth-like planets around stars other than our own; and the DSCOVR satellite that soon will be beaming back images of the whole Earth in near real-time from a vantage point a million miles away. As New Horizons completes its flyby of Pluto and continues deeper into the Kuiper Belt, NASA’s multifaceted journey of discovery continues.”
More science on Michigan in Pictures.
July 7, 2015
Here’s a shot from a place on my Michigan kayaking bucket list – Petit Portal (also known as Petit Arch and Arch Rock by some) and other cliff formations of the Pictured Rocks National Lakeshore. The Lakeshore’s Geologic Formations page begins:
The geologic formations of Pictured Rocks National Lakeshore are most spectacularly represented by the 50-200 ft. sandstone cliffs that extend for more than 15 miles along the shoreline. Sea caves, arches, blowholes, turrets, stone spires, and other features have been sculpted from these cliffs over the centuries by unceasing waves and weather.
The name “Pictured Rocks” comes from the streaks of mineral stain that decorate the cliffs. Stunning colors occur when groundwater oozes out of cracks and trickles down the rock face. Iron (red and orange), copper (blue and green), manganese (brown and black), and limonite (white) are among the most common color-producing minerals.
Geologic history recorded in the sedimentary rocks and surficial deposits of Pictured Rocks National Lakeshore is limited to two widely separated intervals of geologic time, the Late Precambrian, Cambrian, and Early Ordovician Periods (500-800 million years before present), and the Late Quaternary Period (two million years before present to the present).
You can read on for more about each geologic era, and I think that that this report by Lakeshore Volunteer Geologist Robert Rose (pdf) has some graphics that really help to understand how the layers fit together.
June 26, 2015
The Michigan Department of Natural Resources completed their annual June survey of Kirtland’s warbler, one of the rarest members of the wood warbler family that nests almost exclusively in Michigan’s northern Lower and Upper peninsulas, with a few locations in Wisconsin and the province of Ontario. They explain:
“We have a great group of DNR, U.S. Forest Service and U.S. Fish and Wildlife Service staff members, as well as volunteers, who are trudging through young, thick jack pine in the early morning hours,” said Department of Natural Resources wildlife supervisor Keith Kintigh. “The reward is getting to hear that singing male Kirtland’s warbler, which is the way we actually census the population.”
The Kirtland’s warbler census is a tool managers use to compare population numbers relative to recovery goals by listening for the male’s song. Kirtland’s warbler numbers had been very low, under 200 nesting pairs, in the mid-1980s. Michigan became the focus for habitat management, since it has been a primary location for the birds’ reproduction.
Kirtland’s warblers spend eight months wintering in the Bahamas. The males arrive back in Michigan between May 3 and May 20, a few days ahead of the females. The males establish and defend territories and then court the females when they arrive. The males’ song is loud, yet low-pitched, ending with an upward inflection – easily recognized to identify the presence of a Kirtland’s warbler.
Additionally, the presence or absence of Kirtland’s warblers determines if protection of that area is needed and allows evaluation of different habitat management techniques. The habitat requirements for Kirtland’s warbler are very specific; they prefer large blocks of young jack pine, usually hundreds of acres in size. The Kirtland’s warbler is a ground-nester, often using the living branches of 5- to 20-foot-tall jack pine trees to conceal their nests, so jack pine trees must be actively managed. Large areas of sandy soils are planted with jack pine and then cut decades later, on specific intervals, to achieve the perfect-aged stands.
Lots more about this rare songbird, including census results that show a steadily increasing population on the DNR’s Kirtland’s Warbler (Dendroica kirtlandii) page.