In-between scree and talus is "rubble".

Limestone sometimes breaks into pieces as big as your fist, or as big as your foot. This stuff won't flow like scree, but it's unstable and often rolls out from under your foot.
In limestone, the chunks are angular, abrasive, and sharp. Going down-hill, I've lost plenty of blood by rolling down on it.

Scree can be pea-size, up to thumb-size. Fresh scree flows like water, and is almost impossible to walk up, but easy to boot-ski down.

There is never a good route on fresh scree or rubble -- every route is bad. But the good thing about rubble is that it will settle and stabilize when folks walk on it. So you get paths worn into the hillside, and these paths are always easier to walk on that raw rubble.

Talus is usually big enough to step onto, although it might be unstable. Actually there is no upper limit for talus, it can get as big as a car, a house, or bigger.

Here's a volcanic talus slope on Black Butte by Mt. Shasta. Damn! That looks like fun!

i believe that Freedom of the Hills defines talus as rocks that are big enough to step on individually, or something like that (i'm too lazy to go out to my car to get the book and look it up) - i don't see why that can't include flat terrain (e.g. lava flows, river beds, etc) - scree is definitely the small stuff and i suppose it implies that it is loose and on a slope

I hear scree and talus used interchangeably all of the time but to be more descriptive we'll often use the term "boulder field" when the rocks are big.

Bob

paisajeroamericano wrote:i believe that Freedom of the Hills defines talus as rocks that are big enough to step on individually, or something like that (i'm too lazy to go out to my car to get the book and look it up) - i don't see why that can't include flat terrain (e.g. lava flows, river beds, etc) - scree is definitely the small stuff and i suppose it implies that it is loose and on a slope

That's pretty close to what they say -- so I think I will use Freedom of the Hills as a reference! "Talus consists of the larger fragments, usually big enough to step on individually. Scree is smaller--from the size of coarse-grained sand up to a couple of inches across--and may flow a bit around your feet when you step on it."

So now we should have contest to name the stuff in between! Scralus? Talree?

So where does boulder field come in? Does it have to be on flat terrain? The pic of the Ne England talus I would call a boulder field. And what about the flat, slate gray, dinner plate stuff that I've always pictured in my head as talus, does it have a more specific name within the talus family? Scree is easy to define - but certainly not to climb.

Didn't keep footnotes with the references, but did some research a while back and came up with:

scree

The Nordic root means somethink like "skitter".

talus

In French, practically any kind of earthwork is "talus", including the windbreaks between fields in Brittany. I believe in geology, "talus" is reserved for piles at the base of a cliff or slope - that presumably have already found their angle of repose. Whereas scree is often found mid-slope. That includes the "dinner plate stuff", which I tend to think of as large scree.

Generally, though, I use "scree" for small stuff and "talus" for bigger blocks, just as FOTH suggests.

But much of what would be "talus" by that guideline is better described as

felsenmeer

Most Talus is just Felsenmeer after the action of gravity. Unless it's a glacial deposit, the Vose Spur slope is felsenmeer and not technically talus; it originated in place, not by falling from above. (That's my understanding after chatting with a physcial geologist who used one of my photos in a geophysics textbook.)

Many people who dread talus are relieved when I say, "don't worry, it's just felsenmeer." On desert peaks, it is harder to make that point, though.

mrchad9 wrote:You should start from your front door too! Would be awsome to hike for 4-5 days without even driving to a trailhead.

I forgot to mention, for what it is worth, that I am still working on a trail from my backyard up Mount Eddy. Not Mount Shasta, but it should be a pretty nifty climb. Here is a view looking down toward my house from the part of the route that I have been working on:

mrchad9 wrote:You should start from your front door too! Would be awsome to hike for 4-5 days without even driving to a trailhead.

I can do that. Would have to cross a couple of dirt roads to hit something much over 12,000'

For me, if the rocks are large enough to get generally solid foot and/or hand holds, it's talus.

If they're small enough that I have to use gaiters to keep them out of my boots, it's scree.

Some slopes are a combination of both.

Boulders > Talus > Rubble > Scree

Getting hit by a single piece of talus will likey result in injury.
Getting hit by a single piece of scree will likely do no harm.

Think of scree as being the consistency of kitty-litter.
Think of Talus as being like the armour rock on jetties or the banks of storm channels.

http://www.summitpost.org/columbine-peak/150563

Here eons of wind, rain, snow, ice, snow avalanches, earthquakes, water freezing in cracks, have brought down all matter of granite rock sizes on this face. There really is much more finer scree than talus but it is mostly hidden as large talus tends to rest on the top of finer rocks so it appears to be mostly larger talus.

(mouse click to expand)


Of course as large rocks break off the steep face and fall, they can only pile up atop the top layer of large boulders. The smaller rocks however, especially the finer debris after falling can fit between the large talus boulders so given rain and time ends up unseen. Large boulders falling onto the base of the monolithic steep areas have considerable force so are unlikely to stop there thus continue beyond into the larger boulders where they meet their talus buddies. Thus right at the base of the monolithic rock is mostly scree with a few scattered larger boulders.

Below the scree far enough below is likely bedrock. Water seeping through all the rock makes it down to that mostly impervious bedrock then flows along it sometimes forming sheets of ice. The heavy piles of rock atop that base layer of water and ice tends to slide so over time the masses of rock moves away from the monolithic face down the slope. Where a knee in the bedrock gradient probably increases at frame lower left corner, the rock glacier exposes a steep scree face. For we experienced climbing about in such areas of the Sierra, some of the most unpleasantly unstable rock only a fool would gamble playing on. But then after looking at all the much more interesting ways to climb up this face on the monolithic who would bother to anyway?

Sam Henie wrote:Sorry to butt in here but to me Mt Shasta kind of looks like a volcano, which if so would infact hold not Talus, not hold Scree but instead hold Scoria? I maybe wrong here, please correct me if so.

Some of it may be scoria but a great deal of the mountain is composed of andesite and dacite, which is pretty tough stuff compared to cinders. Some of that rock is in the Mud Creek Canyon area, as well ash and other things. Mud Creek Canyon is believed to be the oldest exposed part of Mount Shasta, a remnant of earlier iterations of the mountain. Consequently, there is a lot of different stuff in the area, sort of a big rock concoction. Here is a larger picture to get a sense of the larger area: