Sample Id
Essay by Stella • May 14, 2011 • Essay • 1,590 Words (7 Pages) • 2,471 Views
Sample H 7-2
This sample is a sandstone with two different sized grains in it. The first is the "lighter" color grey which is a courser grain size while the darker colors are a medium grained sand. In this sample there are small ripple marks that can be seen in the section of layers that is right above the quarter in Figure 3. The flow appears to have been moving from left to right because the right side of the ripple is much steeper. Because of the size of the ripple only being about a centimeter the water depth that this sample was formed in was probably about 5-10 cm.
Sample ST 71
This sample is a fine grained sandstone. It is mostly made of fine grained sediment but there is also some courser grains in sections of the rock. It appears that the top of this sample is the side facing the camera in all of the figures. In this sample there are many flutes that have formed because of differences in the weatherability of the sediment in the sample. A flute can be seen in Figure 4. There are also scour marks that can be seen in the sample. This can be created if the current creates a downward erosional direction in front of something. This can be seen in Figures 5 and 6.
Sample 11-2
This sample is a sandstone with course grains. The structure that can be seen in it is dunes. This is because of the laying and cross stratification seen in the sample. The dunes in the sample appear that they were probably about 5 cm tall because of the size that is seen in the sample. These formed in water that was moving fairly quickly and was probably formed in a coastal environment with the water flowing from right to left in Figure 7.
Sample 8a
This sample is a sandstone made with fine grained sediment. The structures that can be seen in the top of the sample are flutes and drag mark casts. The flutes can be seen because of differences in the erosion rates of the two types of sediment. At the bottom of Figure 8 a drag mark can be seen. This is when something, such as a branch or stone, gets dragged across the bottom and leaves an imprint where it crossed. The flow was probably from left to right because the steep part of the flute is on the right and points downstream.
Sample JES Escuminac
This is a fine grained sandstone sample. It appears that there could be two types of structure in this sample. This first is it appears that there could be small dunes near the top of Figure 9. There appears to be some cross stratification with the dip going up and to the right. This means that the water would have been flowing from right to left and depositing sediment on the steep left side. The other possibility is that there could be drag mark casts throughout the bottom half of the rock in Figure 9. This would be caused by a stone or branch being dragged across the bottom of the river.
Sample Escuminae JES
This is a fine grained sandstone sample. In the top of the sample of the sample there are many flutes that have been formed because of the erosional differences in the sediment. There flow of this water appears to have been moving from right to left because of the way that the flute has been weathered, with the steep side weathering in the downstream directions because of eddies that may have formed behind the flute. This sample can be seen in Figure 10.
Sample 10 (Small Quarry in TR sm.)
This is a sandstone sample with fine grained sediments. The sedimentary structure that is shown in the rock is ripple marks. These ripple marks are very small and appear to only be between a half centimeter and one centimeter. This means that the water depth of the sample was probably about 5 cm. Since there is not a huge distinction between the two sides of the ripple and it looks pretty symmetrical the ripple was probably formed by wave action. This can be seen in Figures 11 and 12.
Sample 11-3
This sample is a course grained sandstone or conglomerate because it has course grains with shell fragments in it. This sample has dunes in it that were caused by fairly fast moving flows. The dunes appear to be about 3-4 cm in height. This means that this sample probably formed in about 10-15 cm of water. As seen in Figure 13, there is also cross stratification that formed because of the sediment falling down the steep backslope of the dune. The flow in the sample appears to be traveling from left to right because
...
...