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<br />7 <br /> <br />and the evident rate of movement was then calculated. From their study, <br /> <br />o <br />o <br />c <br />en <br />c.D <br />-.J <br /> <br />Crandell and Varnes found that trees at locality C (Plate II) moved 194 <br /> <br /> <br />feet during the years 1939 to 1952, an average velocity of 15 feet per year. <br /> <br /> <br />Near locality D the average velocity was 16 feet per year for trees that <br /> <br /> <br />could be located on the aerial photographs from 1951 to 1959. <br /> <br /> <br />(2) Measurements actually made on the ground have been made from <br /> <br /> <br />control stakes that were set in 1958. These control stakes were set <br /> <br /> <br />perpendicular to the direction of movement of the flow. The rate of <br /> <br /> <br />movement at locality D was 20 feet per year; at locality C, 15.5 feet per <br /> <br /> <br />year; at locality B, 8.5 feet per year; and at locality A, 2.5 feet per <br /> <br /> <br />year. Comparison of aerial photographs shows that the toe of the active <br /> <br /> <br />flow moved 30 feet in the period from 1940 to 1952 at an average rate of <br /> <br />2.5 feet per year. <br /> <br /> <br />(3) The time-lapse motion picture camera study of the active <br /> <br /> <br />earthflow was carried out during the summer of 1960 at locality <br /> <br /> <br />D. This study showed a constant velocity of 0.04 _.f~e...:e..~t.:,.~.e...r''I._da'. . _~1 <br />or about 0.48 inches of movement per day. .~..~. <br />... ....,~ . .'. i :'-0;' ",'J, <br />'. \, I" .. I' <br />..".:...: .'.t~::::.!. <br />. .. _.. ....... : ~ . "J.....>rll <br />.. _ J'...-_..:.......~:..:....;.........::..:.~::"........ <br /> <br />