l66 SURFACE GEOLOGY. 



the lower blue. A third of a mile to the south, near the landing, two 

 wells at about 50 feet above the sea show 20 feet of gray and 10 feet of 

 blue clay, succeeded by a layer of fetid mud with numerous clam and 

 mussel shells 30 feet below the surface, or only 20 feet above the sea. 

 Casts of clam and mussel shells were found in a brick-yard worked 

 twenty years ago on the shores of Bellamy river, a half mile north-west 

 from Dover point. They also occur in the brick-clay of Eliot on the east 

 side of the Piscataqua. 



Shells * of Saxicava rugosa, Mytihis edulis, Sanguinolaria, and Astarte 

 castanea were found at several places in Kittery within 30 feet above the 

 sea by Mr. John L. Hayes. He also discovered Niicnla Portlaiidica * and 

 Sanguinolaria^" in Portsmouth near Wibird's hill. The shells at this place 

 were 1 5 feet below the surface and 30 feet above high tide, in blue plas- 

 tic clay. Mussel shells are reported at two localities in Greenland (p. 

 163); but farther to the south no fossils appear to have been discovered 

 within the hmits of this state, although there is considerable modified 

 drift which was probably deposited beneath the sea. The shells found 

 in Portsmouth and South Berwick show that an arctic climate prevailed 

 during the deposition of the beds in which they occur ; but the presence 



* Jackson's Final Report on Geology of New Ha7npshire, pp. 94, 121, and 281. 



The shells here mentioned are all species now living. One of them is confined to arctic seas; of the rest, all 

 but one are circumpolar, extending south to our latitude, while one has its northern limit at Nova Scotia, and is 

 most abundant southward. Their synonyms and range, fossil and living, are as follows : 



Nucula Portlandica, Hitchcock; Leda truncata. Brown; Leda arctica and Portlandia glasialis, Gray; 

 Yoldia arctica, Sars (but not of Moller and Mbrch). This shell gives its name to the Leda clay of Canada. Fos- 

 sil in New Hampshire, Maine, New Brunswick, Province of Quebec, Labrador, Norway, and Scotland. Ports- 

 mouth, N. H., is the most southern locality at which it has been found. Now living only in arctic seas; found 

 at Spitzbergen in depths from five to thirty fathoms. 



Saxicava rugosa, Linn.; S. arctica, Deshays. Variable, having been described under five genera and fifteen 

 species. This shell gives its name to the Saxicava sand of Canada. Fossil from New England to Labrador and 

 in Europe; var. distorta. Say, is found in the Miocene of Maryland. Now living in arctic seas, and abundant 

 southward to Cape Cod, and less common to Georgia; also extending south to the same latitude on the Pacific 

 coast of America and in Europe. It occurs from low-water mark to a depth of fifty fathoms. 



Mytilus edulis, Linn. Common mussel. Fossil from New England to Greenland and in Europe. Now living 

 in arctic seas, extending south in the Atlantic to North Carolina and the Mediterranean sea, in the Pacific to 

 China and San Francisco. Littoral to fifty fathoms. 



Sanguinolaria (obsolete); Maco7na, Leach. Two species of this %,e.x\i\i , Macoma Grcenlandica, Beck{M./ra- 

 gilis, Adams), and Macoma sabulosa, Mbrch {M. calcarea, Adams), are common as fossils from New England to 

 Labrador and Greenland, and the latter also in Europe. Both are now living on our coast from the Arctic ocean 

 to Long Island ; the latter is also found in northern Europe, and extends south on the coast of Asia to Japan. 



Astarte castanea. Say. Fossil at Nantucket and Point Shirley, Mass., and at Kittery, Me. Now living from 

 New Jersey to Nova Scotia ; common as far north as Massachusetts bay. Abundant in Provincetown harbor at 

 low-water mark, but more frequently occurring at depths from five to fifteen fathoms. 



Mya arenaria,^^^. Long clam ; the common clam of our coast north from Cape Cod. {Venus vicrcenaria, 

 the round clam, or quahog, is the common species south from New York.) Fossil from South Carolina to Green- 

 land, in Europe, and in the Miocene of Virginia. Now living from the Arctic ocean to South Carolina, — very 

 abundant as far south as New Jersey ; also extending south to France and China. Between high and low tide, 

 and thence to forty fathoms. 



