Question

what materials are deposited in core​

Answer 1

Answer:

Sediment cores were collected from overwash lobes by hammering 1-m sections of 3 inch (7.6 cm) aluminum irrigation pipe into the subsurface, capping the pipe, and extracting it using ropes and a farm jack. The longer pre-Sandy marsh sediment core was collected in similar fashion by driving a 2.5 m section of the same aluminum pipe into the surface of the marsh using a vibracore system consisting of a concrete vibrator and custom fabricated connector attached to the pipe. Oceanfront sediment samples were collected by digging a shallow trench with a hand trowel and collecting approximately 1 L of sediment. Duplicate samples were collected from each oceanfront location. Cores were split lengthwise in the laboratory, photographed, and sectioned into 2 cm intervals for grain size analysis. Sediment samples were wet sieved through 250 μm and 64 μm sieves to separate course from fine fractions. After drying, the coarse fraction was sieved through a sieve stack at half phi size intervals (-1 phi to 4 phi) using a Ro-Tap model RX-29 sediment shaker to permit calculation of the weight percent grain size distribution and mean phi size by weight.

Historical aerial photographs used in this study were downloaded at the highest available resolution from the United States Army Corps of Engineers Coastal Hydraulics Laboratory (USACE CHL) website (http://rsm.usace.army.mil/shore/) (US Army Corps of Engineers Coastal Hydraulics Laboratory, 2014). Historical photos were imported into Google Earth as overlay images and referenced to the longitude and latitude grid by scaling and aligning each image to the current Google Earth view of the study area using landmarks such as Dune Road and the drainage canals cut into the marsh for mosquito control prior to the 1930s.