 So we're going to take a tour of river-dominated deltas. So we're looking at the Mississippi River Delta here. It's flowing into the Gulf of Mexico, which has some waves and tides, but the Mississippi River brings in so much sediment from draining the interior of the North American continent that this delta is really dominated by those river processes. So if we zoom in, we can start to see some of the morphology of the river, and it has the characteristic bird's foot geometry of a river-dominated delta. So the main channel is running in through here, and it's got these branching channels that are a little bit like the toes of a bird. Now I'm showing this in Google Earth, and the color difference here is due to the differences in the imagery itself. We'll zoom in a little more, and one of the things that becomes apparent is the branching of the channels that creates that bird foot texture. So again, here is the main river channel, and these white area are buildings. The highest point in the delta is the levee right along the river channel, and then the greenish areas, the greenish-brown areas here are bays that connect to the Gulf of Mexico, and the greener areas have more vegetation in them. And so this whole area is built up of sediment supplied by the Mississippi River, building out into the Gulf of Mexico. So we're going to take a look at the channel and where it enters into the Gulf. So you can see the levees in the area here and here that are extending outward, and this is the main channel flow, and these brown shadows in the water represent areas that are shallower that reflect the continuation of those levees. This is the zone where you have the maximum accumulation of sediment and would represent the mouth bar facies in a delta. So we're going from part of the delta plane up here down into the start of the slope and right at that change where the bar facies occur. So in this delta there is some wave influence. So if we go to a channel that's further to the east, there are two lines here that light color represents beach deposits. And so the main river flow is coming through here again with the levees on either side. There's a very large positive sediment, but the channel is flowing fast enough that it keeps that open, and then there are waves coming from the bay that's reworking that sediment into these wispy little beaches with a little bit of islands on them. So even in this particular case the delta is dominated by the river, but there's still some parts that are influenced by waves. So another interesting thing is we're going to zoom into the bay areas here. A lot of the top of the delta is accumulating mud and organic matter. And again it's very close to the elevation of the sea level and the Gulf of Mexico. So you end up with ponded water here with little bits of organic island and areas that probably have floating vegetation. Channels bring in some mud that gets deposited. There are places where there's almost no flow and almost no suspended sediment. And so these areas are accumulating organic matter and mud through time. So the Mississippi River is one of the largest rivers in the world and it creates this delta. It does actually have a subsidiary that cuts off to the side. And so the river runs through here through New Orleans and up into this area, but there's a spot up here where some of the Mississippi River gets caught by the Chaffalaya River and is flowing down into the Gulf of Mexico over here. So the Chaffalaya drains part of the Mississippi River and it contains a lot of sediment and is building out, two branches of it are building out these smaller deltas here. One of the natural processes in rivers in deltas is what we call a vulsion. The river will flow through a main channel. Most of the sediment gets deposited in that channel and then the rest of the area outside of the channel tends to subside. The mud loses water and the organic matter decays and gets deeper. And then during a flood the river can end up suddenly changing course. And that's what would naturally happen with the Mississippi, the lower Mississippi going into the Chaffalaya if it weren't for a human engineering constraints to keep that from happening. So I want to show you an example of a river dominated delta for a much smaller river. So the Mississippi River is huge but the Ural River is much smaller and it flows into the Caspian Sea which is an enclosed sea and thus it doesn't have very much in the way of storms or tides. And so the Ural River is coming down and through this desert area here and flowing into the Caspian Sea and again this color difference is the Google Earth imagery and is not natural. So if we zoom into the Ural River delta we can see again that the main river channel is coming out very straight and it's transporting sediment that keeps extending the levees further and further out with the mouth bar and there's nothing to make it change direction. There are breaches in the levees that allow the subsidiary channels to flow and they transport sediment and build out these areas of sediment. So in this particular case there's enough growth of organics, marsh vegetation around the channels that is not classic bird foot in terms of the coastline but you can see that the channels are branching off this main channel. So some of the key features of river dominated deltas in terms of their morphology is this bird's foot pattern and the extension of the channels in straight long direct lines into the standing water. Thanks for watching.