Wood ID?

[Minnesota Daniel]

I got this nice piece from Slabcabber. I have no idea from where it came. Is there enough detail here to ID the Genus? Anyone want to take a stab at it?

[sticksinstones]

Looks like a pretty good example of live oak. Would be easier to confirm with polished piece under microscope of course, but most of what you need to see to make that call is visible here.

[helens]

Sticksinstones, how can you tell what wood by looking under a microscope? Can you determine which wood was petrified by grain sizes or particular patterns?

I have always wondered how petrified wood is ID'd. Is wood type more important than location? Forests always have varied trees in them... so if you find a patch of petrified wood, it's all different colors because an area is petrified at the same time, and that area had say 10 different types of trees/bushes??

Or are all the petrified wood in a given area replaced with the same agate/jasper materials (so same colors and textures), but different patterns in the grain??

[Fossilman]

Might be some "Golden Oak" petwood.....................Awesome!!!

[sticksinstones]

"golden oak" is almost always used to refer to the white and red oak trees found near Stinking Water Creek in Eastern Oregon. There are a couple of problems with that in this case. First is that I've never seen or heard of live oak coming from that area although several different hardwoods are found there. Second is that the mineralization and weathering aren't right for this site. The red accents and the clear agate veins aren't the sorts of features you find in Stinking Water wood, and the pieces that were weathered (vs. fused into the hard basalt flows) tended to be a rusty dark brown color if they'd been exposed to the surface for a long while.

[sticksinstones]

Apr 8, 2012 13:29:31 GMT -5 helens said:

Sticksinstones, how can you tell what wood by looking under a microscope? Can you determine which wood was petrified by grain sizes or particular patterns?

I have always wondered how petrified wood is ID'd. Is wood type more important than location? Forests always have varied trees in them... so if you find a patch of petrified wood, it's all different colors because an area is petrified at the same time, and that area had say 10 different types of trees/bushes??

Or are all the petrified wood in a given area replaced with the same agate/jasper materials (so same colors and textures), but different patterns in the grain??

Petrified wood identification is an offshoot of petrified wood collecting that some (but certainly not all) petrified wood collectors eventually get into. Like any other scientific categorization there are the equivalent of "decision trees" that take you down a path of narrower and narrower options until you arrive at the one (or few) that something is likely to be. Not all wood is preserved well enough to identify accurately, and not all species can be definitively identified with just a cross section cut or with relatively low magnification, but some certainly can and this one just happens to be one of those.

The first thing your eye picks up are the long, relatively thick medullary rays (those rays that look like the spokes of a wheel when you see a log cut in cross section). Oak, beech, sycamore and alder stand out as having the most distinctive medullary rays. Next you look at the pore structure within each growth ring. Every species is different here. Conifers don't have pores at all (the cells look more like fine honeycomb patterns under magnification). Hardwoods (dicots) almost always have rays of some kind and pores arranged between the rays from the beginning to the end of the growth ring. The first part of the growth ring is called the "earlywood" and the last part of the tree to grow each season is called the latewood (obviously towards the outer part of the round).

There are three main groupings of hardwoods:

• ring porous - you see a bunch of pronounced pores clustered at the start of the growth ring in the earlywood
  
• semi-ring porous - pores more evenly distributed through the growth ring but tending towards either smaller or fewer in the latewood
  
• diffuse porous - pores evenly spread through the entire growth ring
  

After that you start looking at features of the pores themselves or particular arrangements of pores, such as how many deep they stack up on the growth ring boundary, or how much the size varies from earlywood to latewood, or patterns that connect the pores either tangentially or radially.

In this case you see a relatively indistinct growth ring boundary where the pores don't change much along with those conspicuous radial bands of pores connected from the earlywood to the latewood almost like bubbles rising up through champagne or something. The two trees with strong medullary rays (in my reference books) that do anything like that are live oak and tanoak. Live oak tends to have smaller pores that produce almost solid looking lines in those connected bands of pores where tan oak they are still a bit more distinct and separated as individual (and somewhat larger) pores.

So in this case, it's a pretty easy ID that doesn't require a microscope to get to because there just isn't anything else quite like it.

There is a book published by a guy named Hoadley called Identifying Wood that is a good intro tutorial on the classification with great examples (in fact this piece looks almost exactly like Hoadley's example of live oak). The only problem is that he deals with modern woods and we're talking about fossils. Many are essentially unchanged, but a true paleobotanist (or a really up tight amateur) with say that it can only be properly called "live oak like" because the fossil world has different names for everything (even if they are unchanged from modern species).

This is the point where I part ways with that crowd and bask happily in the realm that allows me to avoid the academic ivory towers and just enjoy my petrified wood pieces. It's enough to keep my hobby very interesting to me, but I stop short of enjoying papers spent discussing a single species and I've never had any desire to dedicate the time or brain cells to mastering the taxonomy of the hard core fossil crowd.

[Sabre52]

Sticksnstones: I have got to take pics of some of my wood that I'm clueless on as far as ID goes and have you take a look at them. Looks like yu are the go to guy on wood ID and most perplex me.....Mel

[Minnesota Daniel]

Sticksinstones, Thanks for the good explanation. Wood ID was a required class when I got my Forestry BS, and for many years I kept the classic text, "Textbook of Wood Technology. Vol 1", A.J.Panshin et al., McGraw Hill American Forestry Series. I didn't use it enough to justify keeping it around though, so I eventually got rid of it. Now I wish I still had it.

I thought the piece looked a lot like white oak, thanks for narrowing it down.

I don't know where this specimen came from, and I don't know anything about petrified wood from Stinking Water, but the range of live oaks and tanoaks includes and has included Oregon long enough for petrified examples of both kinds of wood to possibly exist there today.

[helens]

Thanks sticksinstones:). I know you have a lot of incredible petrified wood, so you seemed the man to ask:). I really appreciate the long explanation about defining the wood grains.

So basically, in a large petrified wood area, ALL the wood are going to be the same colors and materials, with different tree types (oaks vs pines say) differentiated by their inside patterns, that you see after they are cut?

For example, here in florida, cypress grows side by side with live oaks, palm trees and pine trees in swampy areas. Their cut logs are all going to have very different grains inside. Assuming that they got petrified (not likely here), they'd all be petrified with the same materials because they were petrified at the same time. So would the COLORS be the same in the different woods because they got preserved at once, but the inside grains could differentiate which wood they were originally? Or would the colors be different too?

Maybe that's a dumb question because it's rare to dig up a lot of different petrified wood pieces from different tree types in the same area? I've never been rockhounding except from looking at other people's photos, so I don't know how petrified wood pieces are found.

I know I'm being lazy asking, when I can try to look up the answer myself, but I figure other people might be curious about the answer too:).

[sticksinstones]

I don't know of any examples where the species of the wood played a major role in what colors (impurities in the silica that preserved the fossil) a rock becomes. I can imagine an argument where a wood that is denser might absorb water more slowly and be petrified later in a rapidly changing environment or something like that and helping it pick up different impurities, but the time involved would seem to make that unlikely.

In every forest I'm familiar with it is the surrounding geology that accounts for the colors of the fossil wood and while you might find multiple distinct color habits within a single petrified forest, I don't think the species alone would ever account for this. If it does, I haven't encountered it.

Hope that helps.

-Steve

[helens]

It does, thanks Steve:).

[sticksinstones]

Apr 9, 2012 17:31:51 GMT -5 Minnesota Daniel said:

Sticksinstones, Thanks for the good explanation. Wood ID was a required class when I got my Forestry BS, and for many years I kept the classic text, "Textbook of Wood Technology. Vol 1", A.J.Panshin et al., McGraw Hill American Forestry Series. I didn't use it enough to justify keeping it around though, so I eventually got rid of it. Now I wish I still had it.

I thought the piece looked a lot like white oak, thanks for narrowing it down.

I don't know where this specimen came from, and I don't know anything about petrified wood from Stinking Water, but the range of live oaks and tanoaks includes and has included Oregon long enough for petrified examples of both kinds of wood to possibly exist there today.

I have good examples of live oak from both McDermitt and Sweet Home here in Oregon. White oak is quite distinct from live oak in that it is an easily recognize ring porous hardwood - so much so that you can usually do it without the need for a hand lens. The McDermitt caldera was massive and encompassed many different botanical zones that all flooded and landslided in a cataclysmic event that brought logs from a lot of different areas into different deposits that are mined today over a large (100+ square mile) area.

The Sweet Home deposit is even larger and was once a lagoon that brought in a lot of wood from great distances. More than 60 species were surveyed there by one researcher!

Stinking water is a bit different. This is an "in situ" forest that is still standing (mostly). The massive oak, elm and hickory trees found there were all growing together in the same place at a single point in time. The variety you find is limited to what was growing in this place when it was buried where it still stands today. Pick a species that would likely be in a mature hardwood forest with those species today and you'll likely find it in the Stinking Water fossil record. I certainly haven't seen everything that was found there, but I've been at this a while and I've not seen live oak from that location so far. But it's not really the species so much as the mineralization in this case that tells me the piece you have isn't from Stinking Water. I'd guess it's more likely from the Sweet Home area but it's just a guess without seeing other surfaces.

[Minnesota Daniel]

Sticksinstones, thanks for the excellent explanation of how different kinds of petrified woods come to be found in different places.

Now I'm wondering what kind of wood I might have found here in Minnesota, in river rock, looking for Lakers, which were also present. I'll have to try to get a good picture of the grain. What there is of it that I can make out, is altogether different than this piece.

[sticksinstones]

One of the best things about collecting petrified wood is discovering that it's beautiful "twice". Great pieces are amazing when you view them with the naked eye if they're prepared properly, revealing colors and aesthetics that just hold onto your imagination as you ponder the journey some ancient tree has taken to arrive in your hand as a gemstone. But the first time you look at it through a magnified lens an entire new world opens up to you.

A local agate collector helped me set up a photo station with a microscope to help share that part of the experience and I sometimes include micro-photos with my petrified wood specimens (not always, it's not something everyone cares about and it's a fair bit of work).

But heck, as long as there's an audience assembled that is interested, I'll supplement the basics wood ID discussion with some example photos I've saved in my archives.

Let's start with a couple of conifers:



One of the first order distinguishing features among conifers is the presence or lack of resin canals - those big holes that pitch flows through. Neither of the above show them, but these two do (a pine followed by a juniper):




Resin canals are a bit more random and often intersect the rays and don't have much of a pattern relative to the other structure in the wood (other than they tend to form in the same general part of each growth ring). The pores of hardwoods are different though, and the more interesting category of woods to try to identify. The most dramatic and easy to study are the ring porous hardwoods, like white oak shown here:

which looks distinct in several ways from red oak:

Some other neat looking ring porous hardwoods have similar pores, but lack the big medullary rays, such as this very morphed hickory:

or this one

but they look nothing like the ash or locust trees we often find at McDermitt


or the cherry trees found there


The elm trees (several different sub-species) are also interesting and fairly easy to recognize by the wavy bands of pores in the latewood:



There aren't many trees is in the semi-ring porous group, but live oak is one as is walnut and persimmon (I believe this one is the latter):
or this Sweet Home walnut


The largest and most confusing group are the diffuse porous hardwoods. I won't elaborate as I'm already running late, but here are a few examples to see how pores look when arranged more uniformly across the growth ring (the key feature of this category):






Of course there are huge variations as you go to tropical woods, tree ferns and other exotics - this is just a tiny taste of what's waiting under a hand lens! Sometimes you find mysteries that require help. I'm still researching this one for example (a piece that is also quite dramatic in the macro as a large, perfect round from McDermitt that was only recently excavated:
it looks a bit like elm and a bit like osage orange but not quite right for either.

Sometimes you also find other surprises - like this colony of ostracods (seed shrimp - little water born creatures) frozen in time in this Blue Forest schilderia!


And who knows what this guy was, but the pair of tubes penetrated through multiple slabs of this log (also from blue forest) so I suspect it was a water born creature with a shell of some sort, but who knows? Never did solve this one either:


Hopefully this gives you an idea what might drive a seemingly otherwise normal guy to allow his entire den, driveway, 2-story barn, etc. all be overrun with petrified wood!

[helens]

Great info steve!!

Quick question... what magnification are those photos? I know I haven't seen that much grain in a piece of petrified wood, and the only one I recall seeing is palm wood with any grain at all visible.

Also, these threads are searchable for years and years, ... you may want to put your website in your signature if you want people to find you for more questions:).

[sticksinstones]

Thanks for the .sig suggestion - I'll do that.

It does bring up a potential problem I just thought about. The images I'm sharing come out of a preview gallery I have on my own web server. They aren't actually hosted here on this board and I typically clean this scratch pad area out every few months and start over. I should have thought of that before I used that same folder. Ugh...

But back to the topic at hand. If you look at the photo Daniel posted, you can actually see all you need to with that, which is pretty close to what you'd see with your naked eye. Many pieces can easily be identified with a 10x hand lens. I find the scope useful at around 60X for the detailed stuff, but I then crop photos out of part of the image so it's hard to say what the real effective magnification is (maybe 20 to 50X?)

[helens]

Ahh, ok, it seems higher than that to me, but I haven't really gotten very much into petrified wood, and have learned very little about it. I'm still stuck on the insane micro-details of jaspers and agates... which leads me to another question (it's sooo nice to have people knowledgable enough to answer these types of questions!!)... I know that picture jaspers are petrified mud. I know dino bone are petrifed bones. Are many of the other types of jaspers and agates actually petrified wood?? If not... what were they before they became petrified and filled in with molten stuffs??

[sticksinstones]

There are agate casts that show only the original impression of the log in the hollow that they formed in. Imagine making a lost wax cast where what you actually did was made a "lost wood" cast. The wood is buried in mud, the mud hardens to the shape of the wood, the wood rots away, and the hollow void is filled in like other bubbles with pure silica creating agate casts of the original wood. Paulina, OR produces some amazing pink and gray agate limb casts with incredible external detail (for example). A lot of Hampton Butte material is ultimately just a cast, often jasper and/or agate combined.

Marston Ranch jasper is believed by some to be a petrified bog layer. I've seen large pieces that have features in the top most layer that look like twigs mixed together so I think there is some possible evidence for that claim, but I don't know for sure.

As for other jaspers and how they form, I think it's like anything else at the most basic level - water carries silica in to replace something else slowly over time. But on this point I'm far from an expert and you'd have to switch to find a more learned geologist type to get more insight.

[xXxAlisha91xXx]

I love this thread...

I have some pet wood from Virgin Valley,NV I need help with if you don't mind. I was told by the guy I bought it from, John Church at Swordfish Mining, that there are over 120 species out there and that, for the most part they match more modern species, only being around 16 million years old..

[sticksinstones]

Apr 15, 2012 10:10:14 GMT -5 xXxAlisha91xXx said:

I love this thread...

I have some pet wood from Virgin Valley,NV I need help with if you don't mind. I was told by the guy I bought it from, John Church at Swordfish Mining, that there are over 120 species out there and that, for the most part they match more modern species, only being around 16 million years old..

I'm happy to help identify it if I can. Just get the best photos you can of the end cross section.

I didn't realize Virgin Valley had that many species. That's a LOT of variety. Sweet Home had something like 60 or 70 identified, but it was a lagoon that brought in stuff from all over the region (and potentially the world). Most of what I know of that area is that this is where some great opalized (precious variety) wood is found. I haven't seen a lot of specimens from that area.

Post photos, I'll help as I'm able.