Well yield in these deposits or from bedrock underlying these gravel aquifers 

 is high, averaging 11 gpm (Prescott 1974) . The groundwater table averages 

 about 12 feet below ground surface elevations (Prescott ]974). 



Region 6 (Cherryfield to Calais) 



Bedrock Geology: 



Washington County is underlain by a series of volcanic rocks intruded 

 locally by granitic and gabbroic intrusions. These Silurian and Devonian 

 volcanic rocks represent remanants of a chain of volcanic centers in this 

 area. The volcanic rocks are poorly metamorphozed flow breccias, tuff 

 breccia and tuffs and are interbedded locally with sandstones, siltstones 

 and basalt flows (Gates 1969). 



Structurally, the region has been folded, faulted and intruded in 

 Middle Devonian time, and faulted extensively later during Carboniferous 

 and Triassic Times. The structural trend, like much of the raminder of 

 the Maine coast, is northeast - southwest, but several mapped faults trend 

 northwest - southeast. A large fault with this trend is inferred to run 

 along the St. Croix River estuary basin. 



Seismically, Region 6 has exhibited a history of being much more active 

 than Region 5 (Bloxsom, 1975), especially along a northwest - southeast 

 trending belt centered on eastern Passamaquoddy Bay, Since 1766, approximately 

 twenty seismic events have occurred in the region, including five seismic 

 events of between magnitudes 5 and 6 and including one event over magnitude 7 

 (Bloxsom, 1975). 



Surficial Geology: 



Region 6 is dominated by an ice-contact deposit complex extending from 

 Pineo Ridge in Cherryfield to Lubec. This complex represents a late-glacial 

 advance which left a series of marine deltas and gravelly end moraines along 

 the coastal region (Borns, 1978). In front of this ice stand margin, 

 smaller moraine ridges lie on or are buried within marine clay deposits. 

 Behind the ridge complex, sand and gravel interlobate deposits and eskers 

 rise above the coastal lowlands, and dominate a terrain underlain by thick 

 tills and numerous peat deposits. The eskers may be as long as 80 miles in 

 length (Borns, 1978). 



Soil associations are varied, but are dominated by the clayey Lyman- 

 Scantic and Peru soils. Inland, and associated with the sand and gravel 

 deposits, is the Colter-Adams-Histosols association of sandy, gravelly 

 soils and peat deposits. 



The peat deposits of southern Washington County are numerous and extensive. 

 There are approximately twenty commercial peat deposits containing sphagnum 

 peat within the region (Cameron, 1975). These deposits contain from 15,000 

 short tons to over 8,000,000 short tons of peat. 



(Continued) 

 2-D-9 



10-80 



