June, 1919] 



Fauna of Rock Bottom Ponds 



441 



FIVE YEAR POND. 



Pond II. 



The five-year pond is on Marblehead peninsula, approx- 

 imately one hundred yards from Lake Erie. It fills a rectangular 

 depression in the solid rock of an abandoned quarry. This is 

 the largest of the five ponds, its sides measuring 300, 250, 500 

 and 450 feet respectively. The quarry as a whole has been 

 excavated from fifteen to twenty feet below the surface of the 

 surrounding land. The pond is separated from the limits of 



Station 1 of Pond II. 



this excavation on three sides by a strip of quarry bed twenty- 

 five to fifty feet wide. This was partly overgrown by grasses 

 and weeds. On the remaining side the quarry bed stretches 

 away for almost a hundred yards with only here and there a 

 growth of vegetation. There are abandoned lime kilns at one 

 point. In front of these the shore is made up of soft residue 

 from the kilns. This is the only break in the solid rock enclosing 

 the pond. In one corner the water extended out over this rock 

 and formed several pools. 



• Most of the pond was between eight and nine feet deep with 

 a maximum depth of thirteen feet and eight inches. The water 

 was blue with a slight tinge of green. The transparency disk 



