Sorting Through Peace River Micro-Matrix

[digit]

I gave a friend of mine from the D.C. area a bag of Peace River micro-matrix since he didn't manage to make it down with his family last December for some in situ fossil hunting in the river. His 9 year old son has been all over him since he raised the prospect of going fossil hunting over the school holiday break. Till we can reschedule a time to get out and collect some larger fossils in the Peace, I thought they'd enjoy some fossil hunting on a much different scale during their summer break.

I told him that I'd send some photos and a description of the technique I use while sorting through the micro-matrix so that they would have a good chance of culling some prizes from the fine gravel. It occurred to me that documenting my simple (and unspectacular) method might prove useful to those new to sorting micro-matrix (though experienced micro-matrix sorters will find nothing new and earth-shattering here).

I'm starting with micro-matrix that has been gleaned by double stacking a sifter with 1/4" mesh on top (to remove the larger chunks) and a bottom sifter fitted with a square of 1/16" window screen mesh (placed inside a sifter with 1/4" mesh for support). The fine screen allows the vast majority of sand and ultra-fine gravel to pass through. The micro-matrix gravel was then rinsed, and dried on a tarp on my driveway to make sure it was free flowing and not clumping while I did one final sift. I noticed that my last sift of the dried materials with the sifter fitted with the window screen seemed to be letting a lot of fine black matrix material through along with all of the sand so I switched to an old flour sifter/strainer with a finer mesh to remove most of the sand while retaining more of the fine black matrix. Don't use the one your wife uses for baking--but if you do, try to clean it really really well (and then deny deny deny ).

For those, like my friend, who are starting with a cache of micro-matrix already cleaned and dried, my suggestion is to start with a small sample (a cup or less). I scoop up my sample in a large and easy to handle plastic cup. I use a stack of two paper plates (for sturdiness) that have a decent rim on them to keep any matrix from spilling out and pour a small strip across the plate as shown here:

With a little side-to-side shaking of the plate you can easily spread out the micro-matrix so that it forms an even single layer on the plate making it easy to see each piece. I use a bright LED flashlight and a dental pick that I bought at a flea market to help me sort through the matrix. A toothpick will work fine but I really like the curved shape of this tool as I can use it like a shepherd's crook to easily move the micro-matrix across the plate.

I work my way from one end of the spread-out strip of micro-matrix to the other meticulously looking over all the little granules to see what fossils might be hidden among the fine gravel. As with sifting for larger fossils, when sorting through micro-matrix it is probably a good idea to set aside anything that looks like it could be biologically created for further research. You can always drop it back into the non-fossil micro-matrix tailings later if it turns out to be something geological masquerading as something biological. I usually sweep the fossils I've encountered to the sides of the plate to keep them separated while I work through the line of material in the center. When I'm done with the entire strip I can then easily pick-up the fossils and transfer them into a small lidded container for safe keeping. You may choose to use tweezers to transfer the fossils but I found that I can get most of the fossils to stick to a fingertip long enough to pinch it between a second finger allowing me to securely transfer it to my little container of fossils.

When I've completed a line of micro-matrix and removed all of the fossils I could see, I sometimes give the remaining material a swirl or two to spread it out across the entire plate. Occasionally, a small shark tooth or other easily noticed fossil that was hiding before becomes visible and makes it into my fossil container rather than the discard container. When I'm done with this bit of micro-matrix a simple shake of the tilted plate gathers all of the material to one corner where it can easily be tipped into a (different!) plastic cup. Little by little I work the micro-matrix material from one cup to the other via the paper plate, extracting any micro fossils that I can spot along the way.

I've used magnifying glasses and even a 10x photographer's loupe to assist the naked eye in seeing the fine detail of these micro-fossils but I've found that if you get your eyes close enough to the micro-matrix most fossils can be seen clearly without any magnification at all. Being old and nearsighted I've found it increasingly difficult over the years to read menus in dim restaurants much less detect micro-fossils but I've found that if I sort through the material in the morning before putting in my contact lenses that I can resolve fossils less than 1mm in size with no problem. I also tend to prop the plate up on a cardboard box to raise it up closer to my eyes so that I don't end up with a backache after being hunched down over a plate of micro-matrix for too long--comfort is the key to making this a fun (and civilized) way of hunting fossils.

Cheers.

-Ken

[digit]

Though a lot of the tiny shark teeth in the Peace River micro-matrix tend to be broken or water worn, quite a few nice little ones emerged--some unbelievably tiny (less than 2mm).

There are also quite a number of ray mouth plates many with the distinctive comb-like texture, less common are the Dasyatis type ray teeth with their rounded shapes and dual 'roots', lots of cobble-like drum (and possibly grunt) teeth as well:

There are a variety of other fish teeth (barracuda, pinfish, porgy and others), a few ganoid gar scales, and an assortment of other bits and bobs:

-Ken

[Fossildude19]

Excellent post!

Thanks for this - those who haven't previously searched micros will appreciate it.

Some very good tips here.

Regards,

[digit]

That was the hope. Nothing the regulars to sorting micro-matrix will find revolutionary but hopefully a push up the learning curve so that more folks will postpone the search for a huge meg tooth long enough to appreciate the diversity of the smaller stuff that usually sails quickly through our sifting screens.

Cheers.

-Ken

[Auspex]

Quite daring, working without a sneeze-guard

Really good topic!

[digit]

Quite daring, working without a sneeze-guard

Good thing that I'm not allergic to micro-matrix then. I could wear my face mask that I use while woodturning but that could get messy and obscure your vision if you sneeze into it.

Glad you enjoyed this little topic. I've heard back from my friend and he said TSA stopped him on his way back home and inspected the bag of micro-matrix for explosives (I guess it could have looked like extremely coarse black powder). He says his some immediately got into the matrix and has already found many shark teeth and other fossils. He's hooked--that's another one for our side!

Cheers.

-Ken

[fossilized6s]

Nice post Ken.

I still haven't gone through all of the matrix you gave me yet. But yes, there is a nice variety of species.

Tweezers are a must for micro hunting. And be prepares to get addicted. You've been warned.....

[MarcoSr]

Ken

Great post. A lot of good tips. This post will definitely help folks be successful in finding the smaller specimens in matrix.

Marco Sr.