- Essentially how this particular process works... we have a workflow and we're going to walk through this workflow, step at a time. But as you can see this is a workflow with lots of equations and lots of steps. Let's kind of go through them. So, what we're going to do is we're gonna walk through an example of how this Fulcrum Test is actually done. So as we go through we're going to walk through the particular processes and steps, and go through which steps use what equations, and all that good stuff. The main thing to pay attention to as you go through that is just... what's the gist of the mechanics, what are the pitfalls, what are the things you need to work out. Because in the end I'll give you a spreadsheet that actually does all the calculations for you. So that the spreadsheet isn't a complete black box to you, let's go through what's in that thing. So, this is an example of the Fulcrum Test that we did. This particular Fulcrum Test we're going to look at the Bahariya Formation of Egypt. We did this field work in Egypt, just before things went sour there. And we went out to the Bahariya Oasis, which is in the Western Desert of Egypt. Here's the Bahariya Oasis. There's several really great outcrops out in the Bahariya Oasis with lots of good fluvial channel stories. Probably what the Bahariya Oasis is most known for is if you look right there in that little spot, that's where they dug that guy up. This is Spinosaurus Aegyptiacus, the one that killed the T-Rex in Jurassic Park... was it, three? That's where he comes from. So, let's start with the first step in the workflow of the Fulcrum Test: Data Collection. In this particular case in the Bahariya Oasis, what we have is... we already have a sequenced stratigraphy that's been worked out in this particular area. So, there's sequences and all of these sandstones, in all of these sections, are fluvial channel systems. So what we're going to do is walk into the valley fills. This sequence stratigraphic cross section goes through the valley fills that are the axis between the hinterland that's further in southern Egypt, and the depositional basin which is roughly in the location of the Nyle Delta, slightly to the west. So what we're gonna do... we're going to look at these particular channel fills, starting with the pre. These are going to be Cenomanian in age so these are going to be the very beginning of the light Cretaceous. And we're going to look at the channel fills in this transfer section between the source and the sink. So looking at them, what you do is, you just do basic story analysis, which I won't belabor too much here. I do a fluvial stratigraphy course for APG, as well, where we go in to how to do... how to identify individual channel stories in gory detail. But the basic premise of it is that you'll recognize channel fills by looking at the bar rollover. In other words, you'll do things like look at these accretion surfaces and you'll look for the top and the bottom of them and say, "Ooh, there's a complete bar." Or what you'll do is you'll start and say there's a scour at the base here and there's one individual channel sequence, right there. From the base to the top. From the coarse at the bottom to the fine at the top and say that's one individual bar or channel fill. You'll analyze that and break it out and that will be the first fundamental piece of data that you have. What you're recording, then, is basically a proxy for the depth of the channels that were moving the sediments in your system. We'll also take grain size data. What I do is... I try to go and say let's go to the channel and let's get the lowest cross set in the channel fill, that's not the junky, foul egg scour at the base. But literally, go find the first complete dune at the bottom of the channel sequence, get a piece of that sand. Because what you're going to do is... we're assuming that sand, at that channel was actually transporting when that was a full sized channel. It's going to a proxy for the bedload that those rivers would have moved. What the channel is actually recording in the rock record then is the bankfull channel depth. The bankfull channel depth is going to be what you see on any given day on any given river. That's gonna be the channel size that will hold the channel at bankfull flow conditions. That channel, once you have another drop of water, the channel's gonna spill off to the sides onto the flood plane. So, the bankfull channel depth is what we actually are recording in the rock record in terms of our channel belts and our channel thickness. So there's an example of a bankfull channel fill that's recorded in the rock records. So that would have been the size of that channel in the Belly River Formation in Canada at the time of the Cretaceous when that channel was actually flowing.