Wednesday, August 31, 2011

Orthocerous Fossils

I didn't get a chance to get out yesterday to get any blog photos, so today I'll respond to a request from museum patrons to post information about orthocerous fossils.

The orthoceras mollusk lived in abundance during the Paleozoic Era, between 250 to 750 million years ago. Orthoceras is an extinct member of the class Cephalopoda and is related to the present-day squid and octopus. Numerous tentacles emerging from the larger end of the shell were the most distinct feature of the Orthoceras. The shell was formed as the Orthoceras secreted calcium carbonate from its body and new chambers in the shell were added on as the creature grew.

Found in the Atlas Mountains of Morocco, Orthoceras thrived during the Silurian Period (about 420 million years ago) when the various species evolved into other cephalopods such as the ammonite. The fact that we find their fossilized remains on the border of the Sahara Desert is just one piece of evidence that what is now a desert was once a prehistoric ocean, teeming with strange and unusual life.

The fossils are cut out of limestone deposits.

The bodies of the Orthocerous were long and straight. Like their counterparts the ammonites, these animals had a shell that consisted of distinct chambers that were connected by a tube called a siphuncle, and separated by walls called septa. These chambers were used as ballast in which the animal controlled its balance, which was extremely useful considering they could grow up to 6 feet. They had 8-10 tentacles like their modern-day relatives with an advanced, for their time, nervous system, jaws and eyes. They also had a hyponome, a modified foot shaped like a muscular spout or funnel which they used for locomotion, quickly thrusting out water so they could quickly dart away from predators. They fed mainly on floating plankton, small trilobites and other various gastropods along the ocean floor, or while floating. They could achieve neutral buoyancy by filling up the individual chambers with either gas or fluid though the siphuncle.

Tuesday, August 30, 2011

Dune Sunset

My son, Kevin, and I took a quick hike in the dunes to catch sunset last night.  We headed up into the dunes to what I call Sacred Mountain -- where the cross is located that is surrounded by the ghost forest trees.

The fall colors are becoming more evident.

The angle of the sunset is starting to be more and more south. That is another sure sign of fall. I started to think about how the position of the sunset changes on the horizon and decided to do a little research. Irrespective of where you are on the globe, the sun will always rise exactly East and set exactly West on two days: March 21 and September 21 which are the two equinoxes.

Sunrise is the time when the upper part of the sun is visible, and sunset is when the last part of the Sun is about to disappear below the horizon (in clear weather conditions. If the horizon in the direction of sunrise or sunset is at a higher altitude than that of the observer, the sunrise will be later and sunset earlier than listed (and the reverse: on a high mountain with the horizon below the observer, the sunrise will be earlier and sunset later than listed).

The Earth's atmosphere refracts the incoming light in such a way that the sun is visible longer than it would be without an atmosphere. The refraction depends on the atmospheric pressure and temperature. A higher atmospheric pressure or lower temperature than the standard means more refraction, and the sunrise will be earlier and sunset later. In most cases, however, this would affect the rising and setting times by less than a minute.

The changing position of the sun in the sky from hour to hour and from day to day is of interest to everyone, but especially to architects. They want to know the answers to such questions as, when and how far the sun will shine in the windows of different sides of a building. The diagrams below shows the sun's daily path across the sky at the latitudes of 34° and 42° North.

The sun's position with reference to the horizon is expressed by altitude and azimuth. Altitude is the angular distance above the horizon measured perpendicularly to the horizon. It has a maximum value of 90° at the zenith, which is the point overhead. It is marked on the diagram at intervals of 10° along the vertical line in the center. That line represents the celestial meridian, which the sun crosses at noon.

Azimuth is the angular distance measured along the horizon in a clockwise direction. Astronomers measure it from the south point, navigators from the north point. In the above diagrams which follow the navigators' rule, north is 0°, east is 90°, south is 180°, and west is 270°. Each degree of azimuth is shown in the circular band around the outside of the diagram, and numbers from 60 to 300 indicate the azimuth at intervals of 10°. Lines radiating from the center mark the azimuth at intervals of 5°.

The sun's daily path across the sky on or about the 21st day of each month is indicated by means of seven curved lines. The upper one is for June and the lower one is for December. Each of the other five is for two months. For instance, the path on March 21 is the same as on September 23.

Each path is divided into hours. Numbers along the upper and lower paths show the hours which would be indicated by a sundial. This is known as local apparent sun time.

It is interesting to see how much the sunrise and sunset points move during the year. The azimuths of the extreme positions are as follows:

Date Sunrise Sunset
June 21 61° 299°

Dec. 21 119° 241°

Difference 58° 58°

In other words, the sun rises 29° south of east and sets 29° south of west on December 21. This is for a latitude of 34° N. The arc of the horizon between the east point and the sunrise point is called amplitude. On June 21 it is 23-1/2° at the equator, and increases to 90° at the Arctic Circle, where the sun is up for 24 hours on that day. The value at a latitude of 42° N. is 32-1/2°.

Other facts about sunset:

Sunrise and sunset are defined as the instant when the upper limb of the sun’s disk is just touching the horizon, this corresponds to an altitude of -0.833° degrees for the sun.

Civil twilight lapse of time between sunset and when the sun reaches the elevation height of -6°, in the sky are visible only a few stars and planets particularly bright.

Nautical twilight represents the time the sun takes a pass from -6° to -12° below the horizon, in this period are distinguished horizon line and the main stars.

Astronomical twilight is the time interval between sunset and when the sun reaches 18° below the horizon, the sky is dark, is possible to distinguish the stars up to the sixth magnitude.

Noon in solar time occurs when the sun is at its highest point in the sky for the day, and it is either due south or due north of the observer depending on the latitude.

Monday, August 29, 2011

Quick Tour of Grand Marais

I had a friend visit over the weekend who has never seen the main tourist spots in Grand Marais, so we went on a quick tour.  First we stopped at Sable Falls.  Here is a shot of Sable River and a few of the falls.

We also walked into the dunes from the falls area.

Then we drove seven miles west to the Log Slide area of the Pictured Rocks National Lakeshore.  We certainly had a beautiful day!

Saturday, August 27, 2011

Freighter, Deer, and Rockkhounds

Since I'm trying to make mineral art for my upcoming September and October shows, I haven't had much time to take pictures the last couple of days. So today's posting has just a few shots that I've captured while going about my business.

As I was driving down the hill into town on my way to the museum yesterday,I spotted this freighter heading west past Grand Marais.

On the way home from the museum I decided to drive H58 and spotted this buck on the curve by Sable Falls. 

Yesterday a group of women  from Newago, MI came into the museum. I think they were all related.  They told me they were making their annual pilgrimage to Grand Marais to "get stoned."  I must have looked quizzical, because they laughed and explained that they come up to collect beach rocks that they use in various craft projects.  Two of the group scoured the bargain bins.  No one else has ever pulled out and examined all of the rocks in the $3.00 bin.  They did buy about six of the specimens as well as quite a few other rocks.

Friday, August 26, 2011

Nice Lake Superior Agates

On August 22nd a gentleman came into the museum to show me his agates. I had him write his name and home town on a card -- which is now missing in action. If you see your agates, please send me an email to to give me your name and home town again. Nice agates.

Notice how the agate is still hanging on to its basalt matrix.

Thursday, August 25, 2011

Masse Homestead (Log Slide) Trail and Dune Hike -- Post 2

Today I'll post the rest of the photos from my hike on Sunday. Yesterday and today are very fall-like. Temperatures are cool with a stiff breeze coming off Lake Superior. 

The hike continues with another slightly different view of Au Sable Point, taken from the middle of the hike from the Masse Homestead campground and the bluff over looking Lake Superior.

Here is the view looking east after I reached the bluff.

I have not experimented with the interesting artistic variation you can achieve by playing with an image in Photoshop, but for what ever reason this morning I decided to do so.  The image below was manipulated by significantly increasing the color saturation as well as the contrast, and slightly changing the color hue to be more red.  Normally I do not alter images, other than to slightly change the image to match what it looked like in person.

I found a spot out of the wind, which was blowing around 15 mph.  As I was sitting and having my picnic dinner, I noticed that the variable wind had blown the vegetation in circles, making it appear like the branches were trying to dig themselves out.

While waiting for the sunset, I walked around to capture a few more shots.  There was a little valley with lots of baby white pines as well as the red berries in the ground cover.  What a happy little community.

Enjoy the sunset.

Wednesday, August 24, 2011

Masse Homestead (Log Slide) Trail and Dune Hike -- Post 1

On Sunday I took the time to finally go on a more substantial hike. With the busy summer, my exercise program has certainly taken a nose dive. It was a great day for a hike, though, with temperatures in the mid 60s and a refreshing breeze off Lake Superior. I parked in the pull-off on H58, located half way between Sable Lake and the Log Slide and headed northwest on the trail. Although we have not had much rain recently, the forest seemed quite content.

I came across this downed tree with a colony of shelf fungi.

Or are these "tree agates?"

I also spotted this burl on a tree.  A burl or burr is a tree growth in which the wood grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds.  A burl results from a tree undergoing some form of stress caused by an injury, virus or fungus.  Most burls grow beneath the ground, attached to the roots as a type of malignancy.  Almost all burl wood is covered by bark, even if it is underground. Insect and mold infestations are the most common causes of this condition.

In some tree species, burls can grow to great size. The largest, at 26 feet (7.9 m) occur in Coast Redwoods (Sequoia sempervirens) and can encircle the entire trunk.  When moisture is present, these burls can grow new redwood trees. The world's second-largest burls can be found in Port McNeill, British Columbia. One of the largest burls known was found around 1984 in the small town of Tamworth, New South Wales. It stands 6.4 ft (2.0 m) tall, with an odd shape resembling a trombone. Burls yield a very peculiar and highly figured wood, prized for its beauty and sought after by furniture makers, artists, and wood sculptors.

After around a 40 minute walk, I reached the Masse Homestead rustic campground and headed into the Grand Sable Dunes from there.

Soon after entering the dunes, I came across yet another telegraph pole left over from more than 100 years ago.

As I was walking north to the bluff over looking Lake Superior, I crested a dune and was rewarded with this great view of Au Sable Lighthouse.