The first cruise of the monitoring program occurred just before 
exploratory drilling commenced in July 1981, and subsequent cruises have been 
conducted on a seasonal basis (November, February, May, and July) over a three 
year period. On each cruise, samples were collected at regional stations 1-18 
(fig. 1A) and at 29 site-specific stations (fig. 1B). Regional stations 19, 
20, and 21 were added to the program during the July 1983 cruise. Locations 
indicated by a triangle on figure 1A are sites of sediment cores that were 
taken on other cruises during the postdrilling period. The 18 regional 
stations were positioned to evaluate changes with time over different 
environments within the entire region. For example, stations 13 and 13A are 
thought to be areas of deposition for material winnowed by currents from 
Georges Bank (Bothner and others, 1981; Twichell and others, 1981), as are 
stations 14 and 14A in the Gulf of Maine and stations 7A and 9 in the heads of 
Lydonia and Oceanographer Canyons. Station 15 is in an area of eroding coarse 
sediment. Given the mean current flow to the west on the southern flank of 
Georges Bank (Butman and others, 1982a), the stations in transect I 
(stations 1, 2, and 3) are considered to be upstream controls for stations 
among the major lease blocks (transect II) and for stations downstream of the 
lease blocks (transect III). (Station 13A was added on cruise 4. Because the 
sediment texture varied considerably over short distances at stations 7 and 
14, the positions were changed in the second year of the program to locations 
labeled 7A and 14A; see fig. 1A. Stations 15 and 14A were discontinued after 
the eight and ninth cruises, respectively.) 
The site-specific survey, designed to monitor changes close to a rig, was 
centered around the platform operated by Mobil in block 312 (regional 
station 5), where drilling took place between December 1981 and June 1982. A 
less detailed local survey was conducted with three stations (regional 
