c. Coring Equipment. A pneumatic vibratory coring device designed to 

 obtain continuous sediment cores a maximum of 6.1 meters long was used in the 

 phase II survey operation (Fig. 9). The apparatus is equally effective in 

 penetrating and recovering granular and cohesive sediments; however, a stony 

 till is not easily penetrated and the core barrel will not penetrate coherent 

 rock. The core rig consists of a 10-centimeter steel core barrel, clear plas- 

 tic inner liner, shoe and core catcher, and a pneumatic driving head attached 

 to the upper end of the barrel. These elements are enclosed in a quadrapod- 

 like frame with four articulated legs which rest on the lake bottom. An 

 aluminum H-beam and frame serve as a support structure and guide for the vibra- 

 tor head and core pipe as the core barrel penetrates the lake bottom. The lack 

 of rigid attachment of the coring device to the surface vessel allowed limited 

 motion of the vessel during the actual coring processes. Power was supplied to 

 the pneumatic vibrator head by a flexible hoseline connected to a large-capacity 

 (118 liters per second) air compressor. After coring was completed, the assem- 

 bly was hoisted onboard the vessel, the liner containing the core was removed, 

 samples from the top and bottom of the core recovered, the ends sealed, and the 

 core carefully marked for orientation and identification. The historical 

 development of vibratory coring equipment is discussed by Tirey (1972) . 



Figure 9. A 6-meter-long vibratory coring apparatus used to 

 collect sediment cores is shown being lifted off 

 the platform for deployment on the lake floor. 



A 36-meter-long scow from the U.S. Army Engineer District, Buffalo, was 

 used as the platform for phase II coring. The scow was transported by the 

 Corps tugboat Washington (Fig. 10). 



