4214 FEDERAL AVE 2018-01-02 MF Import

August 1, 2008 File No. 087-4 Peters Residence Page 3 Subsurface Explorations Subsurface explorations were limited to several hand dug holes on the steep slope portion of the survey line. Soils encountered in the explorations were visually classified by the geologist in the field, and are shown on the slope section, (see Figure 2). Geology Landforms in this region comprise a system of erosion modified, glacially sculpted features. The local terrain has formed over Pleistocene age glacial deposits. Deposits of glacial till and outwash sediments from the last glaciation of the area overlie materials from earlier glacial and interglacial periods. The latest occurrence of glacial ice within the area is thought to have taken place during the later stages of the Pleistocene Epoch (some 12,000 to 14,000 years ago), and is referred to as the Vashon Slade of the Fraser Glaciation. Some 3500 to 4500 feet of ice is thought to have overlain the region during this period. Geologic and soil mapping literature reviewed for this study includes: Distribution And Description Of The Geologic Units In The Everett Quadrangle Washington, by J.P Minard, 1981, U.S. Geological Survey Open -File Report 81-248. Soil Survey Of Snohomish County Area Washington, 1983, Soil Conservation Service, sheet No. 39. The USGS mapping shows the terrain in this vicinity to be formed over deposits of "Advance Outwash, (Qva)", and "Glacial till, (Qvt)". The outwash and till deposits are members of the Vashon drift sequence, and are prominent stratigraphic units in the Everett area. The advance outwash consists of a well stratified sand with pebbles and some cobbles. This unit displays reverse grading (coarsens upward), and may become silty and oxidized to a brown color. The advance outwash includes the Esperance sand of Newcomb (1952), and Smith (1976). Locally, the advance outwash is mantled by glacial till. The till consists of a poorly sorted assemblage of sands and gravels in a very dense fine sand or clay/silt matrix. All of the mapped units have been over -consolidated by the weight of the advancing Vashon glacier. The USGS mapping shows this property and the adjacent south slope to be the underlain by the advance outwash sediments. My observations generally confirm the USGS mapping. ( The hand pits encountered dense, grey, slightly silty fine to medium grained sand over the entire height of the slope. The sandy slope core materials appear to be well drained, as no ground water seepage, wetland vegetation, or chronically wet areas are observed. U11