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SHIMER. 



mud, next to suflFer a striking climatic change and finally to deposit 

 another foot or two of sediment. We can not conceive of this as 

 taking place in a comparatively few years. 



Still another factor has a bearing upon the age of the fish-weir. 

 The surface of the street where the fish-weir was found is sixteen feet 

 above mean low tide. Since the fill here is nineteen feet and the 

 lowest preserved horizontal portion of the weir thirteen feet below 

 this, the weir must have been driven into water sixteen feet deep at 

 low tide or twenty-six feet at high tide. That is, to reach the surface 

 of the water at high tide, at the present relation of land to ocean, and 

 penetrate the clay eighteen inches, would require sticks twenty-nine 

 feet long, at the least, and these sticks had a diameter of only two 

 inches at base. Since the construction of a flsh-w^eir under such 

 conditions is practically impossible we must suppose that its erection 

 took place before the land had become submerged to its present 

 depth. If we may judge from the practice of today, the weir was 

 erected when the region was exposed at low tide, or almost so, and 

 covered at high tide. If so, the land has sunk sixteen to eighteen 

 feet since man placed here his fish-weir. 



While none of the above considerations yield anything definite 

 as to years, yet they strongly indicate that the weir is old, very old. 



To briefly summarize, — The remnants of the fish-weir, excavated 

 on Boylston Street, give evidence of man in the Back Bay region of 

 Boston, probably 2000 to 3000 years ago. He built this weir during 

 a climatic period as warm as of? the Virginia Coast at present, and upon 

 a sinking coast. Since its erection the region has sunk sixteen to 

 eighteen feet and suffered a refrigeration to its present climate. 



