11 Mar 2024

Canada's Bermuda Triangle

The magnetism of the north and south poles are what make a compass work. But the pull of those poles is affected by the ground beneath your feet. WHY?

A magnetic anomaly at the eastern tip of Lake Ontario means that a compass reading there may be wrong by as much as 16° in either direction—east or west. How much it changes depends on exactly where you measure. Boats using autopilot can suddenly swerve into the nearby shoals because the readings change so much! Some call this the Bermuda Triangle of the north.

Researchers measured the anomaly to find its strongest point, just 800 m offshore from Gord Downie Pier, in Kingston. Right there, they found a negative effect to the right (making a compass point farther west) and a positive effect to the left (making a compass point farther east). 

Shipwrecking History

The Great Lakes are littered with shipwrecks, and areas like the Thousand Islands (just past the end of the lake) claimed dozens of boats over the years. So it's no surprise that this area has about 200 shipwrecks.
A little farther out from shore is an area called the graveyard of Lake Ontario!

Why Do Compasses Waggle Wildly?

The minerals in the rock underground causes compasses to wiggle, but why is that mineral there? 

There's evidence of a large meteor impact farther off shore, creating a crater 1 km long. Metals in that meteorite may be magnetic, and about 460 million years old. But that crater isn't close to the centre of the anomaly. Could another meteor be involved?

Other Anomalies

There are magnetic anomalies in many other places.

satellite image showing 19 km distance to Charity Shoal, visible as a circle in the water, 19 km south of Kingston, Ontario
There's even another one 19 km further south from Kingston, at Charity Shoal. You can see the circle outline of the crater in satellite pictures! 

Staying in Ontario, look up the one in Temagami!

Read More

L. R. Newitt, L.R. and Dawson, E. "Kingston Harbour Magnetic Anomaly," The Canadian Surveyor.

25 Jun 2023

Dinosaur skin

Did you think that fossils were all bones and nothing more? Nope! Some fossils are impressions left of footprints or tracks. Other fossils are impressions left by skin textures. Sometimes even the tissues of an animal can be preserved, or visible in the fossil. It can be hard to figure out what we're looking at in a fossil of a soft-bodied invertebrate from long ago, but dinosaur fossils are usually easier to recognise. Some later dinosaurs may have had skin rather like an elephant, while others had skin and feathers like modern birds. There are many fossils with skin impressions showing scales much like a modern iguana or alligator!

Here are some articles about a dinosaur fossil, a nodosaur, that was preserved with skin or skin impressions and some of its innards: 

Check out this link at https://earthlymission.com/dinosaur-mummy-science-discovery-nodosaur-intact-canada/ - for fascinating photos of a nodosaur fossil found in Canada!

If you like to imagine what it's like to work in the field gathering fossils, try this link  https://www.huffpost.com/entry/dinosaur-mummy-unveiled_n_59187ca4e4b0fe039b35436f - for a video of the attempt to lift the wrapped fossil onto a truck.

For more than this brief note, look to this link for better explanations. https://earthlymission.com/perfectly-preserved-dinosaur-mummy-last-meal-science-study-nodosaur/ - for a discussion of this nodosaur's last meal, and wonderful drawings of the dinosaur as it would have looked alive.

26 May 2023

The shape of photographs

The shape of a photograph is measured by its Aspect Ratio. This is the ratio of the width of the photograph divided by its height. Until smartphone cameras, the overwhelming majority of cameras used a ratio of 1.5 (width versus height being 3:2). This was the film format of “35 millimetre” (35 mm) cameras.

35 mm cameras were an offshoot of the movie industry. In the 1890s that fledgling industry standardized on that size of film. But the film was difficult to manufacture. Each batch was slightly different and had to be tested for its exact light sensitivity. Oskar Barnack, an engineer at the German company Leitz developed the Leica camera to do exactly that. But people loved that camera not just for testing movie film. They loved it just for taking still pictures. Other companies copied Leitz and produced cameras to use the same film. 35 mm cameras became hugely popular. 

Other cameras were also made, mostly with much larger film sizes, to give higher quality images. These were called “large format” cameras and usually had an aspect ratio of either 1.25 (5:4) or 1 (1:1).

Even when most cameras became digital instead of film, the 35 mm aspect ratio of 1.5 was kept.  However, most cellphones use an aspect ratio of 1.33 (4:3).

So the question arises: what is the best aspect ratio? The answer is that there is no single aspect ratio that’s best for all pictures. Photographers get to crop images and can, and do, choose different aspect ratios for different images. And “standard” print sizes have different ratios. The most common print sizes are:-

4x6 inches – Aspect ratio 1.5

5x7 inches Aspect ratio 1.4

8x10 inches Aspect ratio  1.25

11x14 inches Aspect ratio 1.27

16x20 inches Aspect ratio 1.25

An argument is often made that the most pleasing aspect ratio is  1.618033988749894... This is called the Golden Ratio. It’s related to the Fibonacci sequence of numbers, where each successive number is the sum of the previous two, i.e.

1, 1, 2, 3, 5, 8, 13, 21, 34, 55, …

The ratio of successive pairs of this sequence gets closer and closer to the Golden Ratio.

Curiously, this ratio is frequently found in nature. For example, one can construct a spiral using squares with sides equal to the Fibonacci series, as shown below.   

 This spiral can be found in seashells and sunflowers, to give commonly cited examples. 


The Golden Ratio can also be found in art and architecture, whether consciously incorporated into the design or whether it is just a reflection of pleasing design.

The Parthenon on the Acropolis in Athens, Greece has several elements reflecting the golden ratio.


 The composition of Michaelangelo’s Creation of Adam also follows the Golden Ratio.

Finally it seems that the golden ratio was intentionally included in the design of Toronto’s CN tower. The ratio of the total height (553.33 meters) to the height of the observation deck (at 342 meters) is 1.618.