[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.08,0:00:01.02,Default,,0000,0000,0000,,(Chime)
Dialogue: 0,0:00:01.02,0:00:01.77,Default,,0000,0000,0000,,Hi guys,
Dialogue: 0,0:00:01.77,0:00:03.75,Default,,0000,0000,0000,,the objective of this video is to look at
Dialogue: 0,0:00:03.75,0:00:06.96,Default,,0000,0000,0000,,the bedding structures that form\Nwhen sediment is deposited.
Dialogue: 0,0:00:07.54,0:00:10.61,Default,,0000,0000,0000,,These bedding structures all form \Nin different environments.
Dialogue: 0,0:00:10.61,0:00:12.100,Default,,0000,0000,0000,,And these environments,\Nwhich create the bedding
Dialogue: 0,0:00:12.100,0:00:15.54,Default,,0000,0000,0000,,structures will be discussed.
Dialogue: 0,0:00:15.54,0:00:18.14,Default,,0000,0000,0000,,Firstly,\Nwe will talk about the horizontal beds,
Dialogue: 0,0:00:18.14,0:00:21.42,Default,,0000,0000,0000,,or strata,\Nthat the sediment is laid down in.
Dialogue: 0,0:00:21.42,0:00:25.70,Default,,0000,0000,0000,,Sedimentary rock is stratified,\Nwhich means that it has layers.
Dialogue: 0,0:00:25.70,0:00:29.20,Default,,0000,0000,0000,,These layers have formed because \Nsediment is laid down in
Dialogue: 0,0:00:29.20,0:00:32.08,Default,,0000,0000,0000,,horizontal layers called strata.
Dialogue: 0,0:00:32.08,0:00:35.96,Default,,0000,0000,0000,,Between each layer of strata,\Nwe have bedding planes.
Dialogue: 0,0:00:35.96,0:00:39.91,Default,,0000,0000,0000,,And these bedding planes form because \Nthe region has experienced
Dialogue: 0,0:00:39.91,0:00:43.71,Default,,0000,0000,0000,,a change in depositional \Nenvironment or material.
Dialogue: 0,0:00:43.71,0:00:46.20,Default,,0000,0000,0000,,We can see here in this photo\Nthat we have had one
Dialogue: 0,0:00:46.20,0:00:48.21,Default,,0000,0000,0000,,type of sediment laid down.
Dialogue: 0,0:00:48.21,0:00:51.13,Default,,0000,0000,0000,,And then,\Na change in depositional environment
Dialogue: 0,0:00:51.13,0:00:54.19,Default,,0000,0000,0000,,has caused a different type of sediment\Nto be laid down on top,
Dialogue: 0,0:00:54.19,0:00:57.37,Default,,0000,0000,0000,,in between which is a bedding plane.
Dialogue: 0,0:00:57.91,0:01:01.91,Default,,0000,0000,0000,,We know that the strata towards\Nthe bottom of a series is older
Dialogue: 0,0:01:01.91,0:01:03.22,Default,,0000,0000,0000,,than the strata at the top.
Dialogue: 0,0:01:03.22,0:01:06.57,Default,,0000,0000,0000,,And this happens because the sediment \Nis laid in this way.
Dialogue: 0,0:01:06.57,0:01:11.42,Default,,0000,0000,0000,,Bedforms are formations that occur due to \Nthe movement of wind and water.
Dialogue: 0,0:01:11.42,0:01:15.68,Default,,0000,0000,0000,,Bedforms are created when water or wind,\Nflows over loose sediment.
Dialogue: 0,0:01:15.85,0:01:18.98,Default,,0000,0000,0000,,And the shape and the texture of the \Nbedform depends on the
Dialogue: 0,0:01:18.98,0:01:23.66,Default,,0000,0000,0000,,velocity of the flowing wind or water,\Nand the size of the sediment.
Dialogue: 0,0:01:23.78,0:01:26.15,Default,,0000,0000,0000,,One type of bedform is ripples.
Dialogue: 0,0:01:26.22,0:01:29.01,Default,,0000,0000,0000,,Ripples occur to due the flow of water.
Dialogue: 0,0:01:29.01,0:01:33.52,Default,,0000,0000,0000,,Asymetrical ripples occur when water is\Njust flowing in one direction.
Dialogue: 0,0:01:33.52,0:01:35.36,Default,,0000,0000,0000,,As we can see here.
Dialogue: 0,0:01:35.36,0:01:39.67,Default,,0000,0000,0000,,Symetrical ripples will occur \Nwhen the waves oscillate back and forth.
Dialogue: 0,0:01:39.67,0:01:41.54,Default,,0000,0000,0000,,As we can see here.
Dialogue: 0,0:01:41.54,0:01:45.54,Default,,0000,0000,0000,,These bedforms can be preserved in\Nthe sedimentary rock,
Dialogue: 0,0:01:45.54,0:01:48.28,Default,,0000,0000,0000,,because new sediment \Ncan be deposited on top.
Dialogue: 0,0:01:48.28,0:01:53.08,Default,,0000,0000,0000,,And the formation will remain the same\Nand will be lithified in this shape.
Dialogue: 0,0:01:53.45,0:01:56.27,Default,,0000,0000,0000,,Another type of bedform are dunes.
Dialogue: 0,0:01:56.60,0:02:00.60,Default,,0000,0000,0000,,Dunes form with the same formation \Nprocess as the asymetrical ripples
Dialogue: 0,0:02:00.60,0:02:02.68,Default,,0000,0000,0000,,when they form due to water.
Dialogue: 0,0:02:02.68,0:02:05.62,Default,,0000,0000,0000,,However,\Ndunes form due to the action of wind.
Dialogue: 0,0:02:06.78,0:02:09.75,Default,,0000,0000,0000,,Cross Bedding is another type of \Nbedform.
Dialogue: 0,0:02:09.75,0:02:13.38,Default,,0000,0000,0000,,Cross bedding forms in the process of \Nmaking ripples or dunes.
Dialogue: 0,0:02:13.38,0:02:16.44,Default,,0000,0000,0000,,Whether that be with water or wind.
Dialogue: 0,0:02:16.58,0:02:19.96,Default,,0000,0000,0000,,Cross bedding forms because we have\Na pile up of sediment along the top
Dialogue: 0,0:02:19.96,0:02:21.86,Default,,0000,0000,0000,,of the slip face.
Dialogue: 0,0:02:21.86,0:02:24.38,Default,,0000,0000,0000,,This pile up is being pushed
Dialogue: 0,0:02:24.38,0:02:26.77,Default,,0000,0000,0000,,towards the edge of the slip face,
Dialogue: 0,0:02:26.77,0:02:29.58,Default,,0000,0000,0000,,and soon will slip down the face.
Dialogue: 0,0:02:30.06,0:02:34.82,Default,,0000,0000,0000,,This slip face will then slowly move\Ndownstream as more and more
Dialogue: 0,0:02:34.82,0:02:36.82,Default,,0000,0000,0000,,sediment comes along.
Dialogue: 0,0:02:36.83,0:02:40.83,Default,,0000,0000,0000,,Any additional sediment will continue\Nto form cross bedded layers
Dialogue: 0,0:02:40.83,0:02:44.83,Default,,0000,0000,0000,,in the environment where ripples and \Ndunes are being formed.
Dialogue: 0,0:02:46.04,0:02:49.08,Default,,0000,0000,0000,,Another type of bed form are\Ngraded beds.
Dialogue: 0,0:02:49.32,0:02:53.32,Default,,0000,0000,0000,,Graded beds form when the\Nstrata of the sediment becomes
Dialogue: 0,0:02:53.32,0:02:56.31,Default,,0000,0000,0000,,more fine towards the top of the strata.
Dialogue: 0,0:02:56.31,0:02:59.54,Default,,0000,0000,0000,,This graded pattern is often repeated\Nin a formation.
Dialogue: 0,0:02:59.54,0:03:01.71,Default,,0000,0000,0000,,As we can see here.
Dialogue: 0,0:03:02.33,0:03:07.19,Default,,0000,0000,0000,,Graded beds form due to a sudden period\Nof high energy movement of the sediment.
Dialogue: 0,0:03:07.67,0:03:10.39,Default,,0000,0000,0000,,For example,\Nas we are actually discussed in the
Dialogue: 0,0:03:10.39,0:03:13.09,Default,,0000,0000,0000,,previous video,\Ngraded beds will form when we have
Dialogue: 0,0:03:13.09,0:03:17.00,Default,,0000,0000,0000,,turbidite cones;\Nwhen sediment avalanches over
Dialogue: 0,0:03:17.00,0:03:19.49,Default,,0000,0000,0000,,the edge of a continental shelf.
Dialogue: 0,0:03:19.49,0:03:21.61,Default,,0000,0000,0000,,So,\Nwhen the sediment avalanches over
Dialogue: 0,0:03:21.61,0:03:24.86,Default,,0000,0000,0000,,the edge of the continental shelf,\Nthese turbidite cones
Dialogue: 0,0:03:24.86,0:03:26.20,Default,,0000,0000,0000,,are created down here.
Dialogue: 0,0:03:26.20,0:03:31.38,Default,,0000,0000,0000,,When the sediment is in the turbidite cone\Nthe heavy sediment will settle out first.
Dialogue: 0,0:03:31.38,0:03:36.75,Default,,0000,0000,0000,,The medium size material will settle next,\Nand the fine silt material will remain
Dialogue: 0,0:03:36.75,0:03:41.50,Default,,0000,0000,0000,,suspended in the currents of the water,\Nand will finally settle out on top.
Dialogue: 0,0:03:41.50,0:03:44.66,Default,,0000,0000,0000,,This is what creates our graded beds.
Dialogue: 0,0:03:44.66,0:03:48.66,Default,,0000,0000,0000,,The last thing we will discuss in this \Nvideo are bed-surface markings.
Dialogue: 0,0:03:48.66,0:03:53.34,Default,,0000,0000,0000,,Bed surface markings occur due to \Nalterations on the surface of the Earth.
Dialogue: 0,0:03:53.34,0:03:56.39,Default,,0000,0000,0000,,Mudcracks form when the surface of the \NEarth dries out.
Dialogue: 0,0:03:56.39,0:04:00.74,Default,,0000,0000,0000,,Mudcracks can be preserved in the \Nsedimentary layers when they are covered
Dialogue: 0,0:04:00.74,0:04:02.52,Default,,0000,0000,0000,,by sediment.
Dialogue: 0,0:04:02.52,0:04:06.27,Default,,0000,0000,0000,,These mudcracks indicate that we have had\Nalternating wet and dry conditions
Dialogue: 0,0:04:06.27,0:04:07.95,Default,,0000,0000,0000,,in the past.
Dialogue: 0,0:04:07.95,0:04:10.24,Default,,0000,0000,0000,,Fossils are another type of bed surface \Nmarking.
Dialogue: 0,0:04:10.24,0:04:13.61,Default,,0000,0000,0000,,Where fossils can be preserved within the \Nlayers of sediment,
Dialogue: 0,0:04:13.61,0:04:16.71,Default,,0000,0000,0000,,and they are an evidence of past life.
Dialogue: 0,0:04:17.54,0:04:21.25,Default,,0000,0000,0000,,In summary,\Nsediment is laid down in horizontal beds.
Dialogue: 0,0:04:21.25,0:04:24.76,Default,,0000,0000,0000,,We know these sedimentary layers can\Npreserve past environments,
Dialogue: 0,0:04:24.76,0:04:28.95,Default,,0000,0000,0000,,such as the flow of wind and water over\Nloose sediment.
Dialogue: 0,0:04:28.95,0:04:31.91,Default,,0000,0000,0000,,This flow of wind and water can create\Nbedforms;
Dialogue: 0,0:04:31.91,0:04:34.61,Default,,0000,0000,0000,,such as ripples, dunes and crossbedding.
Dialogue: 0,0:04:34.61,0:04:39.09,Default,,0000,0000,0000,,And bed surface markings such as,\Nmudcracks and fossils can also form
Dialogue: 0,0:04:39.09,0:04:43.21,Default,,0000,0000,0000,,and indicate the environment in which\Nthe sediment was laid down in.