 Tidal flows are really important for redistributing sediment along coastlines and in shallow marine environments. The flow characteristics of tides lead to distinctive sedimentary structures, and in particular there's a large change in the flow speed through a tidal cycle. So I'm going to talk a little bit about the flow speeds and how that impacts the grain size of the sediment that's produced within different parts of the tides. So if we have a shoreline here, the gravitational traction of the moon affects the water levels. It affects the earth as well, but water much more. And so during certain times of the day, the water level tends to be low, and then the tide will go up, but the tide to change, it requires a water flow, and in particular when the tide is going up, there's a net water flow of water towards the shoreline to produce the water that's present here. When the tide is going out, you end up with a net water flow in the offshore direction. And so we know that ripples and dunes provide the directional transport of water flow, and so in a tidal environment you often see evidence of that flow in two directions based on the laminar dip in cross lamination and cross stratification. So this aspect of tides, the two directions of flow, is very characteristic of tides. There are also some other details about tides that make them very distinctive, and that's usually when the tide is high, there might be some waves, but in general the currents are very low. When the tide is low, again the net flow of the water tends to be very low. And so if we look at the flow speed through time, we'll do zero, so this is flow speed, and we'll say that this is on shore, and this is off shore. One of the things that happens when the tide is rising, you start out, say that the low tide is zero here, so the flow speed is zero, and we'll say that this is at low tide. As the tide starts to come in, the flow speed increases and reaches some maximum level, and then as you get closer to high tide, that flow speed slows down again, and the flow speed is zero at high tide. And then as the tide starts to fall, you have flow in the off shore direction, it reaches a maximum speed, and then it comes back up to zero at the low tide. So this first set of flow is the incoming tide, and then this would be the falling or outgoing tide. So we have the cycling of flow, and if we think about the grain size in the zone in here, and the flow speed is very low, we can use our Holstrom diagram, and in this side we have mud-sized grain accumulate. Depending on how fast this flow is, we get much coarser grains deposited here, in this zone right here. I'll just say maximum grain size gets transported, and that may or may not be the same for the falling tide. Sometimes the flow speeds are a little bit different. So you have this really interesting variation in flow speed and grain sizes, and the transport directions that are all characteristic of tidal floods. Thanks for watching.