GO 568 Structural Geology
Helvetide sedimentary cover strata include exceptionally thick Mesozoic (J & K) limestones, which are more prominent toward the east and are strongly deformed but not metamorphosed. Volcanic rocks are generally lacking. This portion is similar to the Appalachian valley-and-ridge province.
During the Eocene and Oligocene, initial uplift of the Alps led to rapid erosion, and sediments were deposited in adjacent marine flysch basins of the Helvetide zone. The flysch strata were subsequently deformed by continuing mountain uplift. Later, during the Miocene, thick terrestrial sediment accumulated in continental troughs north of the mountains--the so-called molasse basin. Once again a comparison can be made with the "deltas" (clastic fans) of the Appalachians.
|Prealps seen from Interlaken Ost. The Pre-Alps are a huge klippe, transported across the molasse basin and thought to be derived from the Pennides. Photo date 4/79, © J.S. Aber.|
|Landslide debris on mountain slope, west of Schwendi. Chalets are situated among large blocks on an old landslide fan below the mountain side. Photo date 4/79, © J.S. Aber.|
|View down the alpine valley between Schwendi and Lütschental. Typical ice-carved valley with steep side walls and a gently rounded floor. The bedrock is entirely sedimentary, namely Mesozoic carbonates--see closeup view in next picture. Photo date 4/79, © J.S. Aber.|
|Cliff exposure of Mesozoic shale and limestone strata; gently dipping portion of a larger fold structure, west of Schwendi. Photo date 4/79, © J.S. Aber.|
|Alpine stream boulders display numerous veins in marble and schist, near Lütschental. Such vein-filled rocks are quite common in mountains. Coin is approximately 1 inch (2½ cm) in diameter. Photo date 4/79, © J.S. Aber.|
|Jungfrau Peak, 13,642 feet altitude, a typical ice-carved horn. Jungfrau Peak is part of the Aar massif, consisting of crystalline basement rocks in the Helvetides. Photo date 4/79, © J.S. Aber.|
|Mönch Peak, 13,449 feet altitude, a classic ice-carved horn. This peak is also part of the Aar massif, consisting of pre-alpine crystalline basement rocks. Photo date 4/79, © J.S. Aber.|
|Bedrock exposure on the side of Mönch Peak displaying dark-colored phyllite and schist. Photo date 4/79, © J.S. Aber.|
|Overview of the city of Bern, its cathedral, and the Aare River. Bern is located in the Tertiary molasse basin of central Switwerland, as are most other large Swiss cities. Photo date 4/79, © J.S. Aber.|
|City of Bern seen from the cathedral tower. The large tile-roofed building in scene center is the Rathaus (city hall). Note the light-brown color of most building walls, which are constructed of soft Tertiary sandstone. Photo date 4/79, © J.S. Aber.|
|Cleaning exterior building walls in Bern. The workers use metal brushes to remove the stained surface of soft sandstone blocks. This sandstone is typical of poorly consolidated molasse deposits of the vicinity. Photo date 4/79, © J.S. Aber.|
Central Europe II.
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