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Geology 399 Finial Project Jonathan W.F. Remo Statistical Analysis of the Lithologic and Structural Controls on Mass Movement in the New River Gorge, West.

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Presentation on theme: "Geology 399 Finial Project Jonathan W.F. Remo Statistical Analysis of the Lithologic and Structural Controls on Mass Movement in the New River Gorge, West."— Presentation transcript:

1 Geology 399 Finial Project Jonathan W.F. Remo Statistical Analysis of the Lithologic and Structural Controls on Mass Movement in the New River Gorge, West Virginia

2 Introduction In the summer of 1998, a study was undertaken to investigate the geologic controls of landslides and landslide deposits within the New River Gorge (NRG). Three study areas of the NRG were selected based on differences in geology in order to compare and contrast the effects of different bedrock and structural geology on the landslides. The upper gorge study area extends from Hinton to Sandstone Falls, West Virginia. The middle gorge study area extends from Glade Creek to the Plateau. The lower gorge study area extends from Keeneys Creek to Fayette Station. Mapping in the three study areas at a scale of 1:24,000 has revealed 125 prehistoric, 51 historic landslide deposits. At least 41 of the historic landslide deposits incorporate mine-spoil. The lithology of bedrock is the most important determinant to the type, size, and composition of the landslides. Joints indirectly influence the orientation of the landslides and the dip of strata effects the type of motion. The prehistoric events have been analyzed to determine long-term relationships between lithology, structure and landslides because historic landslides are more related to human activities than a result of natural phenomena.The upper gorge study area has only 12 mappable prehistoric and historic landslide deposits, the least of the three areas. The bedrock is dominated by weak shale, which weathers rapidly into fine-grained materials. The rapid weathering of the fine-grained landslide deposits makes it difficult to recognize landslide landforms. The fine-grained materials produced by the weathering of shale bedrock are easily removed from the landscape by stream flow. The middle gorge area has 65 prehistoric and 3 historic mappable landslide deposits The upper gorge study area has only 12 mappable prehistoric and historic landslide deposits, the least of the three areas. The bedrock is dominated by weak shale, which weathers rapidly into fine-grained materials. The rapid weathering of the fine-grained landslide deposits makes it difficult to recognize landslide landforms. The fine-grained materials produced by the weathering of shale bedrock are easily removed from the landscape by stream flow. The middle gorge area has 65 prehistoric and 3 historic mappable landslide deposits. The middle gorge area is characterized by shale-dominated valley

3 Introduction Continued sidewalls with a quartz sandstone capped rim. The sandstone is extremely resistant and produces boulders 2 to 4 meters in long axis. The boulders make landslides landforms difficult to erode. Therefore, the landforms are better preserved making, them more recognizable. The lower gorge representative area has 49 prehistoric and 5 historic mappable landslides mappable deposits. The lower gorge area is characterized by quartz-sandstone-dominated valley sidewalls. The Nuttall quartz sandstone member at the top of the lower gorge study area is 20 to 40 meters thick. This unit produces extremely large blocks up to 40 meters in long axis. This blocky material is extremely difficult to erode. These landslide deposits are significant enough to alter the flow of the New River and cause large rapids in the lower gorge. e middle gorge area is characterized by shale-dominated valley sidewalls with a quartz sandstone capped rim. The sandstone is extremely resistant and produces boulders 2 to 4 meters in long axis. The boulders make landslides landforms difficult to erode. Therefore, the landforms are better preserved making, them more recognizable. The lower gorge representative area has 49 prehistoric and 5 historic mappable landslides mappable deposits. The lower gorge area is characterized by quartz-sandstone-dominated valley sidewalls. The Nuttall quartz sandstone member at the top of the lower gorge study area is 20 to 40 meters thick. This unit produces extremely large blocks up to 40 meters in long axis. This blocky material is extremely difficult to erode. These landslide deposits are significant enough to alter the flow of the New River and cause large rapids in the lower gorge.

4 Study Areas

5 Comments There seems to be little if any correlation between joint trends and orientation of mass movement There is a strong correlation between the Slopes of Lower and Middle Gorge There is a strong relationship between the Middle and Upper Gorge Study Areas There maybe a correlation between the joint sets in the Upper and Middle Gorge Study area. A relationship may exist between the orientation of the mass-movement deposits in the Upper and Middle Gorge. Correlation Matrix

6 There appears to be is little if any relationship depicted. Calculated R values are as follows: Upper Gorge Study Area Middle Gorge Study Area Lower Gorge Study Area Pearson product moment coefficient are used to determine if there is linear relationship between the orientation of joints and the orientation of mass movement deposits. Analysis of Joints

7 Pearson product moment coefficient is used to determine linear relationships between aspect and the orientation of mass-movement deposits. There is a correlation between aspect and the orientation of mass movement deposits. The Middle and Lower Gorge Study Areas have the highest R values, and respectively. The Upper Gorge has a lower correlation with an R values of This is due to the lack of mass-movement deposits in the Upper Gorge Study Area. Mass Movement Deposits and Their Relation to Aspect.

8 Comparison of Slopes The Lower and Middle Gorge Study Areas have similarly steep slopes. While the Upper and Lower and Middle and Upper Gorge Study Areas have less similar slopes. Pearson's Correlation Coefficients are as follows: Lower vs.... Middle Gorge Middle vs... Upper Gorge Lower vs... Upper Gorge 0.490

9 Lithologies of the Study Areas The reason for the difference in slope stems from the bedrock geology. The Middle and Lower gorge study areas have more resistant lithologies than the Upper gorge. This is apparent in these pie graphs. The lower and middle gorge have more sandstone in the valley-side walls than upper gorge. Hence the steeper and more similar slopes.

10 Pearson product moment coefficient are used to further determine if there is relationship between the lithologies of the study areas. The Middle Gorge and Lower Gorge Study Areas shows a strong correlation in lithology with a R value of While comparison of the Upper with Lower and Middle Gorge Study Areas shows a much weaker correlation. Correlation of Lithologies

11 Conclusions Mass-movement deposits show a strong correlation with aspect. (I.e. debris slides go down hill) The Middle and Lower Gorge have similar slopes and more similar lithologies than Upper Gorge. This is due to differences in lithology. These differences in lithology effect the preservation and size of mass-movement deposits. Joints trends show no statistical correlation to orientation of mass-movement deposits.


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