Sep 04-10

Past-E-Mail: Cam Notes - 2010: September: Sep 04-10
Sandstone dot rocks    ...scroll down to share comments
Photos by Tim Bertsos
Entry Sentries    ...scroll down to share comments
Photos by Tim Bertsos

Mary Drew at Pasty Central (Mdrew) on Saturday, September 4, 2010 - 07:44 am:

Yesterday we visited the White City sandstone cliffs and today we get a look at some smaller sandstone specimens from Tim Bertsos. Looks like he's a collector of what he calls "dot rocks," all out of that distinctive reddish color that tells you they're composed of sandstone, like those steep cliff walls were. Tim's second shot looks to me like it's from the Portage Entry also, but I think perhaps the North Entry, rather than the South, as that North Entry breakwall is composed of many large rocks. Sitting here on such a jagged perch as these seagulls did, is quite wise, since it's much harder for someone to run at them to make them take flight. Guess Tim's presence didn't phase them one bit.

By FJL (Langoman) on Saturday, September 4, 2010 - 08:04 am:

Good morning to all of my friends. A lot of gull's. Are those Gull eggs or rocks?

By Deb S. (Usedtobeayooper) on Saturday, September 4, 2010 - 08:22 am:

Whenever I see seagulls I think of "Finding Nemo", "mine, mine, mine, mine, mine". Great movie!!!

By mickill mouse (Ram4) on Saturday, September 4, 2010 - 08:31 am:

maybe the seagulls are dotting the rocks...LOL

nice pictures'

By Shirley Waggoner (Shirlohio) on Saturday, September 4, 2010 - 09:06 am:

WOW....what unusual rocks! (LOL, Mickill, you may be right.) Bet there are lots of 'dots' on the rocks in the bottom photo.;)

By Eugene Zuverink (Zube) on Saturday, September 4, 2010 - 10:23 am:

Seagulls are so pretty. My wife and I were sitting north of Saint Ignace on US2 at a picnic table each eating a pastie and I threw a little piece to one seagull I saw, and instantly 50 to 75 seagulls were on us. I have no idea where they came from.

By FRNash/PHX, AZ (Frnash) on Saturday, September 4, 2010 - 10:39 am:

mickill mouse (Ram4):
"maybe the seagulls are dotting the rocks …"

Funny, that was my first thought as well!

This also brings back memories of Boom Trenchard's Flight Path Restaurant (now defunct) near JimsAir FBO at at San Diego's Lindberg Field, a great General Aviation fly-in destination in the 1970s (good food,too!).

You sat about 500' down the main runway, also overlooked the GA runway approach end. Great view! Seats along the windows had the local control tower communications piped into speakers. Popular with Navy Pilots too. It did have a short appearance in the movie Top Gun but if you blinked you missed it.

Oh and the signs on the restroom doors: "Buoys" & "Gulls"! <grin>
Nate (Nalwine) on Saturday, September 4, 2010 - 11:05 am:

Anyone have any pictures from the 20' waves on Lake Superior last night/today? If you do please post them :)

By eugenia r. thompson (Ert) on Saturday, September 4, 2010 - 12:03 pm:

Don't have pictures of the waves, Nate, but looking at how rough even Portage Lake is today (on the MTU webcam since our BridgeCam is frozen again).

By David Soumis (Davesou) on Saturday, September 4, 2010 - 12:46 pm:

yep ...I've always thought those white dots were from seagull drops. it scrapes off

By mickill mouse (Ram4) on Saturday, September 4, 2010 - 02:04 pm:

We went to Port Huron one time, when we lived downstate, and parked by the Bluewater Bridge amd I put something on the dashboard. All of a sudden a seagull landed on the hood of the truck and started pecking at the window. Poor thing thought it was outside. An elderly couple started laughing and took a picture of it. Had to hit the wipers a couple of times to get it to move.

By Cheryl Rozman (Cotton) on Saturday, September 4, 2010 - 03:20 pm:

Seagulls are nothing but pests.Had one --it on my shoulder at Fisherman's Wharf & it was awful!!!!

By Dr. Nat (Drnat) on Saturday, September 4, 2010 - 03:34 pm:

The white spots in the red sandstone are reduction spots, which are a result of the chemistry of the sandstone and groundwater when the rock was formed. Red sandstones, like the Jacobsville, get their colour from a little bit of iron in the cement that was precipitated by groundwater and holds the sand grains together into solid rock. Because of the oxygen in the atmosphere and water, most of the iron is oxidised, making it red. In a few places the iron is reduced, leaving the sandstone the white colour. The iron doesn’t get oxidised in those small zones because something in the rock used up all the oxygen before the iron could get it. Usually that something is a small bit of organic matter that was decomposing in the sand or a mineral that is more easily oxidised than iron. The area around that little bit of organic matter or mineral becomes oxygen poor, making the white reduction spots you see in those rocks.

By Richard Wieber (Dickingrayling) on Saturday, September 4, 2010 - 03:51 pm:

I was told, years ago, that we must not pester one legged gulls because they are reincarnated great lakes sailors. And we all know that an old sailor wouldn't lie to us, don't we?

By Rob (Robze) on Saturday, September 4, 2010 - 04:16 pm:

Thanks Dr. Nat. Learning something new is a good thing, thanks.

By kay Moore (Mskatie) on Saturday, September 4, 2010 - 04:18 pm:

Dr. Nat...I like your version of the white dots better than the gull doo-doo :O>)

By laurhMN (Keeweewannabee) on Saturday, September 4, 2010 - 05:18 pm:

I have used so many of the polkadot rocks in gardens and as stepping stones at my home in MN. I receive many questions as to the origin of the dots, stripes and various patterns that occur. Now I have an explanation! Thank you Dr Nat!

By Donna (Donna) on Saturday, September 4, 2010 - 07:16 pm:

VERY cool! Thank you Doc!!

I read someplace that if you find a rock with a hole through it, and you could run a string/necklace through's known as a Fairy Stone and it will protect you!

By Capt. Paul (Eclogite) on Saturday, September 4, 2010 - 08:25 pm:

To add to the Doc's comment; sandstones with such reduction spots aren't found in all places in the Keweenaw. The Freda hardly has any, and the Jacobsville in some areas has an abundance of reduction spots. It is not fully known why this occurs....

By Dr. Nat (Drnat) on Saturday, September 4, 2010 - 09:01 pm:

I forgot to mention, the reduction zones don't have to be spots. Sometimes the white areas are lines. This happens when oxygen-poor water flows along a crack in the rock.

Other red-bed sandstones (like the Abo Formation in New Mexico, the Chinle Sandstone on the Colorado Plateau, the Entrada Sandstone in Utah, and the Aztec Sandstone in Nevada) also have areas with abundant reduction zones.

By Thomas Baird (Thomas) on Saturday, September 4, 2010 - 09:48 pm:

Nice photography.

By Marianne Y (Marianne) on Sunday, September 5, 2010 - 08:27 am:

Thank you, Dr Nat and Capt Paul. ((I must admit, that before your explanations, I, was thinking it was as a result of the seagulls.)

Cotton, I agree with you on your thinking on the seagulls, without question! When we were UP there a couple of weeks ago, we went out to the (what I call the east entry, because I keep them straight that way), and parked for a little while. Two of my sons walked out to the light, while my husband waded in Keweenaw Bay, and I sat in our car with our dogs and watched the seagulls all over the place. I might add that we see them here in mid-Michigan, 25 miles inland, bugging people at fast food restaurants and around dumpsters at grocery stores, etc. And yes, my sons did get some interesting pictures of the light. They were surprised it was so far out to it.

By David Soumis (Davesou) on Sunday, September 5, 2010 - 10:41 am:

we were at the Mackinaw City of my kids dropped a fry and there must have been a thousand gulls instantly. Of course they then had to drop and throw a few was quite a site until the manager came out and told us to knock it off. They crap all over the cars and stuff plus all over the parking lot.

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