now this is what i was talking about with those subtropical oceanic gyres don't get confused okay this is your california current that was part of the north pacific subtropical oceanic gyre this is your gulf stream this is part of the north atlantic subtropical oceanic gyre you know the direction of these currents right the california current runs from higher latitudes back to the equator the gulf stream runs from the equator to higher latitudes bringing warmer water up north but we're talking about long shore transport here completely different so don't get confused by those i want you to realize that your biggest storms on the east coast are coming from the north atlantic and your biggest storms on the west coast are coming from the north pacific therefore because it's storm related the direction of your long shore current on both coasts east and west is from north to south so right along the beach you've got usually sand transport heading south on both the east and west coast make sure you know that okay so southward transport along atlantic and pacific coast this does not correspond to the major current direction of those subtropical oceanic gyres do not get confused by that i will ask a question on this all right beach compartments all right so now that longshore current is kind of segmented slightly okay so what does the beach compartment consist of right number one rivers supply the sediment well that used to be the case here in san diego but now we just dredged the end once again that's coming in next lecture i don't want to get too involved with it yet all right so but just in in a theoretical point we're going to say beach compartments if i ever ask you this right i'm going to say rivers supply the sediment so there's number one number two sand gets swept down the coast by the longshore current okay all right that sounds right cool and then number three it finally ends in these submarine canyons um out into the deep water so number one let's redo it again river supply sediment number two beaches grow downstream right so that long shore currents bringing the sand down down down making the beaches here or here or here or here largest and the number three sediment gets drained off through the canyons let's take a look at all these beach compartments all right look at this we've got the santa barbara beach compartment starts from like point conception makes its way south um and you end up putting all the sand eventually into waimea canyon or magu canyon santa monica starts right after those canyons and ends up putting it down redondo canyon the san pedro compartment starts just right here in la and then actually goes down the newport canyon and then here where we have where part of the oceanside compartment starts in dana point and actually goes down la jolla canyon so ocean side compartment dana point to la jolla and each one of these beach compartments ends with a deep water canyon okay depositional land forms all right so now we're going to be thinking instead of we started with erosional landforms i want you to know about depositional landforms too even though they're less related to what we have going on we do have some of these all right because some parts of our coastline have more deposition than they have erosion not as nearly as many though so erosional landforms are more important for here in the west coast of california here in southern california especially but these depositional landforms i want you know about as well so we got a delta check it out river coming in bringing a bunch of sediment and they end up in all these little channels like this creating these tiny little islands this sediment is deposited right at the mouth of the river okay the only place that these deltas occur are places where there's not a lot of waves right when there's not many waves then this delta can actually build up but if there are waves it just gets ripped away okay so we've got waves long shore drift is from the left-hand side of your screen to the right-hand side of your screen and what you're going to see is okay rivers supply the sediment right bunch of sediment if this longshore currents taking it this way what we're going to see is a spit form this is a spit forms just downstream right if and the spit is just a long skinny thing of sand that's kind of starting to maybe lock in this whole lagoon area but right now it's an estuary so if you let this continue on you'd end up forming a bay barrier okay these are all terms that i'm going to want you to know here's another spit if it formed all the way across this would be a bay barrier that's what you see here um another thing i want you to do is turn below right tumbleo is forming because you have an island and the waves focus on the island but then it's super small behind it the wave action i should say so it's a very low energy environment behind the island therefore it's like a summertime beach and builds up sand behind it i'm going to show you pictures of all these so for the delta here's an example here in canada this is a huge delta it's giant okay it's really really big why is it so big because there's not many waves here right so a lot of the places where these deltas are like i said not many waves therefore i haven't seen very many deltas in my life because i'm always looking for waves but maybe waves aren't your thing deltas might be your thing if they are and you end up going to a delta take some pictures send them to me you'll be famous in my lectures for as long as i do it for so hopefully that happens like i said the shape of the delta depends on the energy of the ocean basin larger deltas happen in smaller wave energy ocean basins okay spits we're going to talk about these bay barriers we're going to talk about these tumblers we're going to talk about these check it out here's a spit it's shaped by the long short current so if you're looking at this spit can you tell me which direction the longshore current would be take your time yeah exactly so i'm hoping you said it's from the top of your screen to the bottom of your screen not from the bottom of the screen to the top of the screen all this has to be forming from all this longshore current causing the sand to slowly build up there you go there's your arrow now the salt marshes form behind these spits so slowly but surely these spits form notice these little like they almost look like wings right little wings that are formed this one formed first then this one then there's another one forming right but notice this area right here it didn't end up becoming a bay barrier right because if all the sand moved across it'd be a bay barrier forming a lagoon behind but that didn't happen because this flow is strong that river flow is ripping out so there's a big kind of rip current right here and it's ripping away the sand so it's a struggle between the long shore current depositing sand here and this river ripping the sand away forming this dynamic process and forming this structure called a spit here's a nice diagram to go off of as well if the longshore current was flowing in the opposite direction you would see the spit form on this side of the bay and therefore this here here's your here's your current moving out ripping away all those and you can see these little wings i was telling you about there they are there's those wings and the salt marsh behind those wings there's the salt marsh behind the wings there you go it's all happening looks just like the cartoon picture right there you go that's what a spit is now depositional landform number two right or number three actually we talked about deltas we talked about spits here is a bay barrier also known as a bay mouth bar i like to use the term bay barrier so this used to be a spit and now it's formed all the way across you see that this whole area this is a bay barrier forming a lagoon behind and this lagoon is slowly going to fill up and disappear i got a question for you will this uh lagoon become more or less salty this water that's right it'll become more salty because it's slowly going to be evaporating right and become less and less water more and more solids therefore more and more salty okay so a bay mouth bar or bay barrier occurs when a spit grows across a bay joining headlands right just like this boom there you go there's your lagoon in the back here's your bay barrier bay barrier lagoon in the back lagoon slowly but surely fills in over time from deposition so from other maybe rivers coming through filling in with a little bit of sediment and it'll disappear all right what's a tumbler right another one um a tumbleo occurs because the island like i said here's your island it blocks the waves so the waves break out here and then back here it's really small low energy and that low energy is kind of like a summertime beach that just builds up sand you can see little people right here walking so this is a large thing okay this is very large scale sand accumulates right behind this island and this here this connection of sand is called the tumbler here's an idea of it as well so this tumbler we got waves hitting out here but then it's small waves happening just behind forming the sand like a summertime beach here's another beautiful example of a tumbler here's your island blocking the waves forming this unbelievable nice tumbler behind now the place that you could see these all of these landforms including the tumbleo the bay barrier and the spits you're gonna see these the closest spot that i know is if you go to the gulf of california um the next time i travel through there i'm taking pictures for sure and they'll be in here that's really my goal is to have all pictures from either my students so please send me pictures if you have any that are like this or pictures that i took right um it's amazing what you see in the gulf of california in places like moulihae and loretto if you go down there you'll see these exact kinds of landforms it's depositional it's low wave energy you'll see it there okay so take a look next time you go down the uh baja peninsula go to the east side and take a look through moulihan the red on you'll see all these beautiful spots