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Archive for the ‘Rocks & Gems’ Category

Cave shaft – Canada, originally uploaded by Mic2006.

In the same area where we discovered the Tooth Tube, a cave that we have been clearing of a glacial plug of clay, we have also found numerous deep shafts, aligned along joints they tend to be deep and narrow with fluted sides and moss around their upper lips. To a caver, a cave shaft is generally indicative of something that might be occuring lower down. Often, but not always, the shaft represents the dominant passage of water as it drops beneath the surface, and as Marcus Buck had pointed out in the excavation of the ‘Birth Canal’ at Olmstead in the Eramosa Karst, “Usually if you follow where the water goes, it takes you on to tunnels”.

This particular field of shafts and pits is in an area that is not too far north of Toronto, Ontario , Canada. For a Torontonian I believe it is one of the coolest things to do near Toronto.

The shafts that we found occur in a plateau that sits well above a large body of water and though the local water table is sometimes known to be perched, it would appear that by looking down into some of these holes, it must still be way below the surface. Many of the more slender shafts appear to be relatively debris-free. Wider shafts tend to be clogged with soil and leaves and logs. They can approach a diameter of about 10 feet in width and we speculate that like in the St. Edmunds System, water may have entered the underground at a time when the area was beneath a kilometer thick sheet of ice. As the pressure head built up, the water beneath the glacier was forced down tiny crevices, down to the bedding plane, and then out at the base of the plateau. Most of these shafts are at the bottom of a conical depression of between 10 and 25 feet in depth. In an old manuscript Martin Davis mentions a stream that he had dye traced that seems to take most of the surface water from this area and drains it out at a single point in the cliffs around the edges of the plateau.

Strings of shafts line up along the general orientation of local joints and we intend to plumb the depths of one such shaft this weekend. Our best case scenario is to find an open cave tunnel that requires minimal digging to clear it. I dropped a bolder down one deep shaft where I could not see the bottom and after an impressive pause I heard the muted ‘thunk’ of tin that had been pounded by my falling missile.

In one relatively shallow shaft we have found a crevice that seems to drop down into a water worn passage beneath, that will be our first priority. It was hard to get a good look at the passage as the crevice above still requires some cleaning, but I had the distinct impression it was human sized and floored with cobbles like we found in the Wasteland Waterway – still to be pushed to its endpoint.

For a final look at where we got with our excavation on the Tooth Tube – Click for cave video of the Tooth Tube here.

Check out the shaft at C-H sink, it is also in an area where sinks dimple local fields. Check out a short video of the C – H sink here

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An unseasonably warm day – early March found JC and I visiting Southern Ontario on a search for abandoned gypsum mines.

Where both the Grand River and the Nith River meet there is the quaint though somewhat aged town of Paris. It has the appearance of having been passed by progress, there are brick and barn board sided buildings in the downtown – somewhat neglected, but full of character. Large mills had once tapped the water power and the mining of plaster of Paris leaves a fascinating terrain of forgotten rail embankments, inexplicable hollows and gullies along the river bank, weirs and beaches where barges once loaded up the chalky material from underground and of course decayed and vine choked foundations.

I was inspired to photograph this backstreet business, ‘The Grand River Experience’ it appears that they offer canoe and kayak rental as well as tours down the river; I believe it was on their website that I had my first glimpse of a riverside gypsum mine – supposedly one of many that are around there. As you might have guessed, there is a connection between ‘plaster of Paris’ and the coincidence of this calcium sulfate material being mined from a conglomerate that underlies the area. It is said that the gypsum comes from Silurian age lenticular deposits on the south east flank of the Algonquin Arch.

Devil’s Cave is one example of a local feature where running water has dissolved away the gypsum and having washed the conglomerate out, there are small cavities lived in by a colony of beavers and decorated by spectacular white speleothems and flowstone.

Having now visited this area several times and followed apparently sure leads, both JC and I are somewhat disillusioned as to the prospects of finding open gypsum adits – though a cave is far preferred. Everything seems blocked up real well (with the exception of a single adit along the river bank downriver from the town). Crossed shovel and pick symbols on a map (available on the internet) generally leads you to a spot where you’ll find an undercut that is pretty much buried in countless tons of soil.

Having long been fascinated by industrial archeology, urban exploration and various forgotten tunnel explorations I’d like to know of where there are old gypsum mines around Paris where an interested person can visit and actually go underground?

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There’s a crevice that cuts under a cliff face. It leads to an underground lake that just goes on and on. Dan and I spent about two hours underground wandering waist deep in water. I am thinking that the mine is somewhere between 100 and 170 years old.

Back in the 1820′s and 30′s there was a serious demand for building stone in Southern Ontario; Whirlpool Sandstone was one of the most valued materials. It was extracted from a  layer just above the Queenstone shale.

Near Belfountain you can see this rock at the base of Church’s Falls. See the chapter on Belfountain on page 69 of my book “Rockwatching; Adventures Above and Below Ontario” The rock that came from there was a maroon color and was used to build Queen’s Park and various buildings at University of Toronto. Down here in the more southerly areas of the escarpment the Whirlpool Sandstone seems a lot higher on the escarpment than it is further to the north. It is also more varied in color and I am told that it is possible to find azurite and malachite in chert pockets in that rock.

Anyway the construction of the Welland Canal generated a great deal of demand for building stone as did the increasing size of the urban structures around the “Golden Horseshoe.” Finally around 1900 the skyscraper came into being. The strength of the modern skyscraper comes not from its rigid outer shell but from its internal steel girder skeleton. This change in design meant that standard construction stones suddenly lost their market and materials such as Italian and Indian marbles started showing up. They formed a thin veneer as did materials like glass, labradorite and granite. they were in no way responsible for the buildings structural integrity. Sandstone had seen its day and the mines closed shortly thereafter.

Some years back year Jeff Mirza and I traveled up to Belfountain to see if we could find our way into one of these underground tunnel systems. Apparently there are several deep passages above the hairpin bend as you wind down from Belfountain into the Credit Valley. Jeff had even seen a picture of a shaft in the forest with a ladder leading down into the mines. After a day of trudging along the hillsides we came to the conclusion that the entrances had all been blasted shut. It was not the case here. The tunnels lie wide open. It was as much a historical exploration as it was a geological one. The rooms were quite low though generally very wide and initially lit by small shafts that cut up to a brambly plateau above. The vegetation was so thick that it was almost impossible to progress on the surface, nevertheless, the shafts of light on the underground lake were really picturesque.

At times high banks of rubble rose out of the water and it was necessary to slither along on our bellies. In places deeper into the mine calcite deposition had made a hard, translucent shell across the top of these banks and we had to be careful so as not to damage the profuse clusters of soda straws that were forming on the roof. The bats seemed quite perturbed by our arrival in their world and somebody was cheeping angrily from up a crack in the roof. On several occasions they fluttered by and I could just catch glimpses of their chaotic flight. I was surprised by the extent of speleothem formation in the mine. I had believed that under good conditions soda straws could grow at about an inch every hundred years though in remembrance of a winter excursion Jeff and I had done up a storm sewer in Hamilton a few years back, that one inch can be quite drastically stretched.

As we waded through the lake there were tunnels that branched off in every direction, the air  seemed dead and the steam that rose from our coveralls clung to us. it made photography quite difficult.

The water was so still and clear in one spot that I was surprised by the ripples when I crawled right into a pool. We continued on along a mound that was just beneath the surface. Dan wandered off to the side into the deeper water and suddenly found himself hip high in really treacherous mud. I had a similar experience moments later and we decided that further exploration would have to be done with an air matress. Up ahead it sounded like a heavy rainstorm and I think that there must have been a spot where the water was pouring in.

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Silver Crater Mine – Bancroft, originally uploaded by Mic2006.

I paid my $2 at the house of the landowner whose property I had to cross and then headed off into the woods. I’d heard that the path to the mine was about 4 miles long (it was not), but possibly longer, and the route was signposted (it was not- or should I say, it was in places).

The attraction at the Silver Crater Mine is a pit and adit that are rich in Betafite crystals. I found a lump of calcite with the top of one such crystal sticking out. It looks like the dull grey top of an octahedron. The adit burrows through a granular calcite which in my opinion does not make for a well-supported roof. So my advice about the adit is to stay out. I went in about 10 feet before coming to this decision.

Aside from radioactive betafite, there is also apatite (turned red by radiation), large books of biotite and horneblende.

See video of the directions here – Directions to the Silver Crater Mine

See video of the mine entrance to the Silver Crater Mine – here (silver Crater Mine) entrance)

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IMGP1080, originally uploaded by Mic2006.

I picked up some beautiful red Rubellite tourmaline at the 2011 Bancroft Gemboree yesterday. This fellow had 2 grades, the lesser grade he was selling at $40/carat and by weight the specimen that I picked out amounted to $64. Admittedly the color was not quite on a par with the higher grade, but there was less in the way of inclusion and the cut was of good symetry and deep so no light was spilling out a window.

I initially decided to go hardball and said that if he wanted to go $40 for the specimen it was sold, but he did not so I went away for a few hours, thought about it and came back and gave him his price. I suppose the value was what I was willing to pay for it and I really love red tourmaline.

You can see the gem that I bought on the tray to the left of the picture.

All in all, some of my favorite vendors were missing from this year’s venue – in particular Alpine gems and a couple of the cut stone dealers that I have so enjoyed in the past, also the better gem vendors seemed more evenly distributed between the upper and lower venues with what seemed a bigger focus on fossils than in the past. I was pleased to see the CGA presence and I had a discussion with my former tutor who advised me that the likelyhood of finding a natural alexanderite of the size that I mention was very slim indeed (with reference to a specimen that I had recently viewed but was unable to clearly see inside because I was in a rush and was yet to clean it).

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P1010585, originally uploaded by Mic2006.

One of the more exciting events of my rock-related year is the Bancroft Gemboree where i can schmoose with other rock-focused people. You absolutely know that this weekend the accommodation in Bancroft and for miles around will be booked solid so either I will be staying with my sister or possibly in Peterborough.

At the Bancroft Gemboree there is every natural crystal from the beautiful to bizarre – a booth of Columbian emeralds, Pakistani Peridot dealers and Russian fellow who sells black power pyramids of some unnamed substance. You stand there long enough he’ll have you convinced to put one in your living room – an investment that will turn your life around. Well if you believe that crystals will heal your warts, you’re well advised to see him as you’re likely thinking along similar lines. I’ll get a picture if he’s there this year and see what he has to say.

If you are into crafting, beading, crystals or geology, or just looking for gems, rough or cut, the Bancroft Gemboree is an event that goes beyond the material presentation of those goods, it’s a cultural event that bonds a motley crowd of locals to a throng of rockhound and crafting visitors. There are two huge venues, though I have always found that the better gem-stuff is in the venue lower down the hill. The best deals at the gemboree are typically outside at the top of the hill though last year I was disappointed.

Maybe next year I’ll get a booth and flog my upcoming Ontario cave book there.

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IMG_8705, originally uploaded by Mic2006.

JC, GW and I returned to this karstic area to make an attempt on this pit. This is but one sinkhole of many in this area – over 50 mapped nearby, all overlying a buried karst that likely hides caves that we would very much like to find.

We have taken a short break from Wasteland Waterway as it can get quite intense if you do it every weekend. Instead we thought to involve ourselves in something a little less serious – the C… sink was exactly what we needed. It was a sinkhole that had been dye traced by a local university, but inexplicably, with such a perfect pit, they never had the curiosity to descend it.

We carried our ladder for around a half hour through tangled, bush, nettles and along the edge of a corn field until we reached our destination.

At the end of a narrow, steep sided gulley we followed a barely flowing stream as it dribbled over a ledge for a free fall into the underground.

Down below the water pattered down upon us like a cloud-burst, we were soaked in seconds, but we stayed to clear debris from the mouth of a small triangular shaped tunnel. As GW points out, with a little persuasion we will be able to remove the boulder that blocks our way and then we’ve got a going cave dig.

We now have the luxury of one promising cave dig and 2 caves with virgin passage known only to myself, JC and soon to be Greg and Marcus.  For Ontario that really is quite remarkable and it becomes increasingly apparent that the karst is there and if you know what to look for, the tunnels soon make themselves apparent.

A short break next week as I’m off to the Bancroft Gemboree – I never miss it. I hear the CGA is there so I’ll stop by to touch base with old collegues. Gems are another of my interests.

Still working hard at getting the next cave book out – it’s looking good. If you are cave-interested, especially in Ontario caves, geology or geography I’m sure you’ll appreciate what I’ll have to offer – again discretion with locations, but like opening a treasure box if you’re a cave searcher you will be totally energised by what you hear and see.

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