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The deposits lying below salt marshes often have properties which render inadequate the conventional peat samplers with spring type locks. These deposits may be thick and highly compressed at the lower levels, but even at the upper levels shell beds, thick clay and sand layers may offer great resistance to the sampling device. Under such conditions, the spring of the Davis type peat sampler breaks or bends when the tool is subjected to strong pressure while locked in the open position. In addition, highly compressed deposits often prevent the spring from engaging in the manner necessary to lock the sampler in the open position. During the summer of 1959, I sampled a salt marsh deposit using a Davis type sampler. I soon had to discontinue sampling until a device was constructed that would function in the deposits encounteredl. Figure 1 shows the basic features of this device. Its primary purpose is to obtain samples where the deposits are hard, compressed, and thick. Its design emphasizes durability and eliminates the wveakness of the spring of the Davis type sampler so that it can be subjected to great force during all phases of the sampling process. It can be quickly and economically built, replaced, and repaired and its durable construction permits the obtaining of a rather large sample. The sampler I used obtained a core having a diameter slightly in excess of 1 in. Figure 1 shows the sampler, which consists of a barrel (1) of relatively thin steel tubing sharpened at one end, a steel bushing (2) welded iniside the upper barrel (1), a key-way (3) cut through the bushing (2), a driving coupling (4), a shaft (5) screwed and pinned into the driving coupling (4), a key (6) welded and pinned to the shaft (5), and a driving point (7) screwed and pinned onto the shaft (5). The driving rod (8), not actually a part of the sampler, is best made of segments of steel rods of convenient lengths having a tapered or otherwise specialized thread. For best results the parts should be made of tough steel, preferably stainless, in sizes approximately proportionial to those shown in the diagrams. However, I had good results with a driving rod (8) of 3/ in. pipe, a driving coupling (4) from a 38 in. to '2 in. reducer coupling, a shaft (5) of '2 in. pipe, and a driving point (7) of scrap metal turned down on a lathe. A bushing (2) with a key-way (3) was cut from steel pipe and placed in the upper part of the barrel so that it protruded slightly. A weld was then placed around the lateral protruding walls of the bushing (2), thereby fixing it to the barrel (1). This weld was supplemented by drilling a few holes through the barrel (1) and partly into the bushing (2), and then filling these xvith a weld. The device is driven to the sampling depth in the closed position (Fig. 1-A). At this depth, the operator pulls up on the drive rod (8) until the driving point (7) contacts the bushing (2). At this point, the key (6) has cleared the key-way (3), and by turning the drive rod (8) one half turn, the key (6) is positioned 180 from the key-way (3). Downward pressure on the drive rod (8) causes the key (6) to contact the upper surface of the bushing (2) and pushes the barrel (1) into the deposit, thereby cutting out a sample. The key (6) replaces the spring of the Davis sampler S~~~ |
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