Oldest rocks ever!

Baffin Island's "old" rocks

Some rocks were found on Baffin Island in the Canadian Arctic that give clues to the composition of the Earth shortly after it was formed. The rocks  are only 69 million years old. However, their isotopic composition suggests that they were formed from the material of the Earth’s primitive mantle. As such, they provide extra evidence for the composition of that mantle and refute some hypotheses about it.


What is limestone made of?

The coccolithophore Gephyrocapsa oceanica under scanning electron microscope

I’ve been looking at a lot of local limestone and sandstone lately. Sandstone is made of sand, often in tiny annual layers. But limestone is made of the remains of tiny sea creatures. To be specific, much of it is formed by coccolithophores, which are distinguished by an ‘armour’ of  tiny plates of calcium carbonate. Trillions of their skeletons formed the basis of some of the world’s most interesting landscapes.

They still dump 1.5 billion kg of calcite into the ocean every year.

Rocks at about.com

About.com has a lot of nice articles about rocks and rock formation by Andrew Alden. Already this morning, I’ve learned how to tell siltstone from shale or sandstone or mudstone, what a thunder egg is, that agate and chert are both types of chalcedony, that alabaster is a kind of travertine, and how banded iron formations were formed. They date back to when the earth’s atmosphere mostly free of oxygen, and any oxygen produced by photosynthetic bacteria quickly bonded with iron in the earth’s crust.

Highway 97 in BC closed by danger of rock slide

That's not a path, it's a crack!

That is not a path, it is a crack in the hillside!

The main highway in the Okanagan Valley, Highway 97, has been closed north of Summerland. It will stay closed until at least Monday while geotechnical engineers examine a dangerous slab of rock poised above the highway. A crack above the rock widened about 10 cm in the last few days. The crack was noticed by workers who were widening the highway.

Geotechnical engineers say the fissure is several feet wide and is around 30 feet deep. Rough estimates are that around 300,000 cubic metres of rock are moving on the face.

The shutdown severs the main artery between Penticton to Kelowna in B.C.’s Okanagan region.

Arthon Construction… estimates it will take at least a few days to repair the face….

Northbound motorists are advised to detour via Highway 33 or Highway 3. The alternate route will add at least a few hours to the trip.

If it’s granite, that’s around two million tonnes of rock.

The photo below must be taken from the north because the lake is on on the left.

Lake Okanagan, looking south along Highway 97

Lake Okanagan, looking south along Highway 97

Pseudoscience: the expanding Earth

Eric at The Dynamic Earth blog dissects the nonsense of “the expanding earth” pseudoscience.

Spot the Canadian Shield!

This map is from One Geology.

Hat tip to Ontario-geofish.

June in Kenora

Blogger Laurence Hunt sends some pictures of Northern Ontario after a month of sunshine and rain. It looks splendid: The Kenora Palette.

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