kilometers long and 1.8 kilometers wide is clearly defined on the two tracK.- 

 line profiles by its irregular subbottom character and almost 22 meters of 



sea-floor relief. The segment, named Six Mile Reef on the charts, represents 



the most southerly advance of very late Wisconsin Glaciation following the 



Harbor Hill episode. Its proximity to the Old Saybrook Moraine probably 



represents a seaward extension of that moraine, but additional subbottom data 

 are needed to verify this. 



In the western Sound, segments of the Elmhurst Moraine were identified on 

 several seismic records as subtle, broad mounds covered by about 5 meters of 

 modern sediments (Fig. 9). 



Position of the Elmhurst Moraine in Figure 9 is close to what Newman 

 (1977) theorized; at Execution Rocks it is about 1.8 kilometers wide and 

 strikes east-northeast parallel to the Connecticut shore in an irregular and 

 lobate line. South of Stamford Harbor the moraine is marked by several prom- 

 inent shoals and to the east it is perched on a bedrock high and comprises 

 the Norwalk Islands. Its trend continues toward Bridgeport and is no doubt 

 responsible for the Lordship outwash head southeast of Bridgeport (Fig. 9). 

 Another submerged outwash head located south of the town of Milford very 

 likely marks the terminus of the moraine west of New Haven Harbor. The 

 Branford Moraine segment east of New Haven is probably a continuation of that 

 outwash head, but the proximity of the Madison, Old Saybrook, and Six Mile 

 Reef segments suggests the glacier front had several small-scale advances and 

 retreats in eastern parts of the Sound. 



In addition to the actual moraine features found, a number of highly 

 stratified and elongate shoals containing very coarse-grained sediments are 

 present in the Sound which apparently owe their origins to glaciof luvial or 

 ice-contact processes. Acoustic profiles and core 7 at Cable and Anchor Reef 

 (Fig. 11) show that about 10 meters of very coarse sand in the form of forset 

 strata rests on a bedrock high which continues south toward Long Island and 

 meets the shore at Eatons Neck. Its proximity to the moraine forming the 

 Norwalk Islands suggests a relationship; however, its general north-south 

 orientation is normal to any other glacial deposition feature. A similar 

 condition exists for Stratford Shoal in the middle of the Sound south of 

 Bridgeport (Fig. 11). The shoal is 5.4 kilometers long with a north-south 

 axis, and the seismic profiles suggest that the presence of stratified till or 

 outwash overtop a bedrock high. The exact origins of these anomolous north- 

 south features are not definitely known, but their form, forset-type strati- 

 fication, and coarse sand and gravel composition suggest that they are outwash 

 deltas from the ancestral Housatonic and Naugatuck Rivers. Additional inves- 

 tigations are needed to better understand their origins. 



Long Sand Shoal off the mouth of the Connecticut River is another sea- 

 floor feature that originated from very late Wisconsin glacial processes. Its 

 east-west orientation, asymmetric profile, and high relief suggest a morainal 

 origin, but acoustic lines over the shoal show a high degree of internal 

 stratification with forset strata dipping south; bedrock beneath the shoal is 

 very high but there is no evidence of till reflectors. Cores obtained from 

 the shoal show a composition of clean and generally moderately sorted sand, 

 which suggests that it was a delta-front or outwash head that has probably 

 been narrowed and significantly increased in length by Holocene estuarine 

 processes during the past 12,000 years. 



29 



