296 Annals of the Carnegie Museum. 



Presque Isle are seldom able to establish themselves around a lagoon, 

 which has been separated from the lake for more than two or three 

 years, so that the age of the cottonwoods will indicate very closely the 

 age of the bar and its enclosed lagoon. 



Ridge No. 7 at Cedar Point rises to a height of from twelve to six- 

 teen feet above the lake, and from the age of the largest cottonwood 

 Moseley concludes the ridge to have been formed by a great northeast 

 storm, which occurred on September 11, 1878, or the one which oc- 

 curred on August 15, 1879. Probably both contributed to the making 

 of the ridge. Ridge No. 6 is also dominated by cottonwoods. It rises 

 to a height of nineteen feet above the lake, and must have been formed 

 by northeast storms during the very high water of 1858 to 1862. Among 

 the other plants on this ridge were found several red cedars, ten feet 

 or less in height, and, as the cottonwoods are short-lived trees, Moseley 

 based his records of the age of the older ridges mainly upon the data 

 furnished by the cedars, assuming from indications on the ridge-sec- 

 tion, on the bar-section, and on the Marblehead spit, that the ridges 

 were nearly or quite forty years old before cedars started to grow 

 upon them. 



Following these methods Moseley calculates the approximate dates of 

 formation of the various older ridges as follows : Ridge No. 5, A. D. 

 1724; Ridge No. 4, A. D. 1684; Ridge No. 3, A. D. 1594; Ridge 

 No. 2, A. D. 1504 (this ridge showing a cedar stump cut probably sixty- 

 five years ago at an age of about two hundred and ninety-seven years); 

 Ridge No, i, A. D. 1429. 



Following much the same methods for Presque Isle as did Moseley 

 for Cedar Point, the writer found that there is considerable similarity 

 in the probable ages of certain corresponding ridges on the two penin- 

 sulas. The probability is that most of the great northeast storms 

 which affected Cedar Point also affected Presque Isle. 



The bar between lagoon " Aa " and Lake Erie (see map of Presque 

 Isle, Plate XXII, 218) was evidently formed about 1902-3, some of 

 the little cottonwoods around the banks of the lagoon being in their 

 fourth year in 1906. This structure is not shown on the Lake Survey 

 Chart of Erie Harbor and Presque Isle, as issued in 1903. 



Between " Aa " and " C," on the banks of " C," are cottonwoods 

 which were three inches in maximum diameter in 1906. The lagoon 

 " C " was thus likely cut off from the lake in 1894 or 1895. Between 

 " C " and " D," along the shores of the latter, are cottonwoods with 



