Chapter II.— GEOGRAPHICAL AND PHYSICAL CONDITIONS. 



1. GEOGRAPHY. 



The general geographical features of the region may be seen at a glance by reference 

 to charts 223, 224, and 225". Vineyard Sound has a length of from 15 to 17 nautical 

 miles, depending upon the limits arbitrarily chosen,' and a width of from 3 to 6 nautical 

 miles. Its main axis bears from northeast to southwest. The southeastern boundary is 

 constituted by the island of Marthas Vineyard, the northwestern by the Elizabeth Islands 

 and for a short space by the mainland of Cape Cod. At its eastern end Vineyard Sound 

 passes imperceptibly into the far wider Nantucket Sound, while to the westward it 

 opens freely to the Atlantic Ocean. It is connected with Buzzards Bay by a series 

 of narrow straits, of which Woods Hole is a type. Through them the tidal currents are 

 very swift. These straits separate the Elizabeth Islands from the mainland and from 

 one another. There are no streams of any consequence emptying into either Vineyard 

 Sound or Nantucket Sound. 



Leaving out of consideration certain shoals and the zone immediately adjacent to 

 the shore line, the depth throughout Vineyard Sound ranges between 6 and 18 fathoms, 

 most soundings lying between 10 and 15 fathoms. There is in no sense a progressive 

 deepening of the water as we pass toward the western end of the Sound, although some 

 of the greatest depths (18 fathoms"^) occur in the vicinity of Gay Head and Cuttyhunk. 

 At least one sounding as great as this has, however, been made back of Middle Ground 

 Shoal, and depths as great as 17 fathoms occur at more than one point in the eastern 

 half of the Sound. As a rule, the lo-fathom line runs within a half mile from shore, 

 though mention must be made of an elongated shoal reaching well toward the middle 

 of the Sound and extending throughout about half its length. This is known at its 

 eastern end as the Middle Ground, the opposite end being called Lucas Shoal. In the 

 former portion the water may be no deeper tuan 4 feet or less in depth at mean low tide. 



Buzzards Bay has a length of about 25 nautical miles, as measured from the railway 

 station known as Buzzards Bay to the Hen and Chickens Shoal. Its main axis is nearly 

 parallel to that of Vineyard Sound, from which it is separated throughout the lower 

 half of its length by the Elizabeth Islands. Elsewhere it is bounded by the mainland of 

 Massachusetts. At its northern end and along its entire western side the shore line of 

 Buzzards Bay is very irregular, being indented by a considerable number of estuaries, 



o These and other geographic and hydrographic charts used in the present report are the work of Mr. W. F. Hil!. formerly 

 draftsman in the Bureau of Fisheries. 



^ The region explored during our dredgings extends a short distance into what would probably be commonly regarded as 

 belonging to Nantucket Sound, though there is. of course, no definite line of division between the two. 



c Our own soundings give 19^ fathoms at one point {Fisk Hawk station 7683). while the greatest depth indicated on theCoast 

 Survey chart for Vineyard Sound is 18 fathoms at mean low tide. Perhaps the phase of the tide is partly accountable for this 

 difference; perhaps it rests upon an error of observation. The depth recorded by us for station 76S2 (19 fathoms) is quite likely 

 due to an error. Otherwise no serious discrepancies have been detected between the Fish Hawk .soundings and those of the 

 Coast Survey. In general our soundings (Fish Hawk and Pkalarope), while not always taken with great care, are believed to 

 be close enough appro.ximations, especially when the variability in depth throughout the extent of the Bay and the Sound are 

 considered. 



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