Figure 9. The ODGS Research Vessel GS-1 used to tow the seismic 

 equipment and locate core sites. 



3. 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. 10), The apparatus is equally effective in penetrating and recovering 

 granular and cohesive sediments; however, the core barrel will not penetrate 

 consolidated rock or pebbly till. The core rig consists of a 10.1-centimeter 

 steel core barrel, clear plastic inner liner, shoe and core catcher, and a pneu- 

 matic driving head attached to the upper end of the barrel. These elements are 

 enclosed in a quadrapodlike 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 vibrator 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 com- 

 pleted, the assembly was hoisted on board 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). 



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 tug- 

 boat Washington (Fig. 11). 



17 



