Throughout the course of four years of diving, a number of 

 process observations have been made. The storm-generated gravel 

 ripples have been discussed above. Concave-upward bivalve shells 

 are found on the surface in many muddy basins. These are in a 

 less stable position than if they were being swept by strong 

 currents, and may represent either settling, death position after 

 disarticulation by starfish, or bioturbation tipping. In any 

 case, they argue for low current velocity and infreguent physical 

 disturbance. Shells in talus aprons (Figure 13) , on the other 

 hand, are randomly oriented or convex upward, suggesting more 

 vigorous current reorientation. There is a ubiguitous amphipod 

 tube and hydroid mat or "turf" that stabilizes the mud surface in 

 basins. Where this mat is disturbed by larger organisms, scour 

 of fine-grained sediments is more likely. Bioturbation is 

 ubiguitous, from deep, 10 cm diameter burrows in the muddy basins 

 (Figure 14) , to narrow worm and decapod burrows on the sandy 

 surfaces. The relative degree of bioturbation is a measure of 

 freguency of physical disturbance. Future studies will integrate 

 this factor into sediment facies and process reconstructions 

 similar to those by Howard and Reineck (1972). Finally, human 

 disturbance is common in the muddy basins. Drag marks from trawl 

 doors and rollers leave grooves a few centimeters deep and up to 

 2 cm wide. These can overturn rocks, rip up the "turf", and 

 otherwise disturb the biota. 



Pelagic settling was noted from the abundant "marine snow" 

 in many of our dives. This may adhere and accumulate in the 

 basins, but is not evident as a long-term build-up above wave 

 base. Sediment samples recovered from the traps in 1987 are 

 obviously only a preliminary indication of the suspended 

 fraction, but they are consistent. Analysis of the inorganic 

 fraction revealed mean grain sizes of 8.1 to 8.4 phi (Figure 15). 

 Averaging the accumulation over the 2 3 day period suggests an 

 accumulation rate of 0.5 + 0.2 g/cm 2 /yr. This is consistent with 

 submersible observations of a roughly 1 cm thick fluffy organic 

 layer on the surface of much of the inner shelf. Under a 

 microscope, much of the coarser part of this material is seen to 

 be diatom tests and sponge spicules. This organic mud is not a 

 permanent component of the sandy Kennebec paleodelta or sandy 

 zones in Saco Bay, and is presumably reworked by winter storms. 



We speculate that low-density turbidity currents may carry 

 sediments into the deeper basins, especially when generated from 

 submarine slumps. Kelley et al (1987a, Figure 22) and Belknap et 

 al. (1986, Figure 4) have demonstrated the presence of active 

 submarine slumps in the Maine nearshore. An examination for 

 graded beds in cores, or detailed process studies with 

 nephelometer and sediment traps will be reguired to demonstrate 

 the turbidity current hypothesis, however. 



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