GENERAL REVIEW AND CONCLUSIONS 



TOPOGRAPHY 



Charles J. Fish, Dixector 

 Buffalo Museum of Science 



CONTENTS 



Page 



Topography 173 



Physical hydrography 175 



Chemisuy 176 



Microplankton 177 



Horizontal distribution and seasonal 



variation 177 



Vertical distribution 177 



Factors of production 178 



Macroplankton 178 



Macroplankton production 178 



Volume of plankton 179 



Faunal zones 187 



Macroplankton community 188 



Vertical distribution 189 



"Marine relict" community 189 



Fish 191 



Pollution 192 



Chemical observations 192 



Bacteriological observations 192 



Conclusions 194 



In compiling the results of the investigations of 

 1928 and 1929, the outline adopted for the prelim - 

 inary report published on the first season's work has 

 been followed. This makes possible more readily a 

 comparison of the two years ' work. In the present 

 paper greater attention has been given to the second 

 year's findings except where significant differences 

 occurred. For a detailed account of the investiga- 

 tions in 1928 the reader is referred to the Prelimin- 

 ary Report (Fish et al. 1929), particularly for data 

 on the topographical and bacteriological studies 

 which were not repeated in 1929. 



Since it was not possible to retain the scientific 

 staff after the termination of field work, the Individ - 

 ual reports have necessarily been prepared simultan- 

 eously as independent units. In the present review an 

 attempt is made to correlate the data when possible, 

 and to include certain analyses omitted in previous 

 discussion. The two seasons' results will be consid- 

 ered jointly. 



Lake Erie is located in a shallow glaciated basin 

 240 miles long, with an average width of 40 miles 

 and an area of approximately 9, 633 square miles. 

 It is the shallowest of the Great Lakes, only about 

 40 percent of its total area exceeding 20 meters and 

 less than 9 percent exceeding 30 meters. The pres- 

 ent survey included 2 of the 3 natural sections of the 

 lake, the eastern or Deep Hole area having a maximum 

 depth of 64 meters and the Central or Great Plain area 

 having a maximum depth of 25. 5 meters. The west- 

 ern section including the islands in Ohio waters is not 

 considered in the present report. 



The Lake Erie basin has been formed for the most 

 part in Devonian shales with a small amount of lime- 

 stone and sandstone, and most of the entering streams 

 drain through glacial deposits of sand and gravel. In 

 cross section the eastern part of the lake is bounded 

 on either side by sandy beaches or limestone cliffs 

 merging into coarse sand, and beyond the influence 

 of land outwash, into basic shale or faulted rock bot- 

 tom free from sedimentary deposits except near the 

 mouths of the larger creeks. The shale outcrop on 

 the American side is smooth and forms a narrow along- 

 shore band whose outer margin parallels the 10 -meter 

 contour. The Canadian outcrop is much broader, ex- 

 tending to the 15 -meter contour, and is composed of 

 honeycombed shale. The Central Basin contains a 

 thick deposit of clay mud covering a great portion of the 

 lake and whose outer margin for the most part parallels 

 the 20 -meter contour (fig. 63). 



The clay mud area extends to the shore only in 

 such places as Long Point Bay and Erie Harbor where 

 outwash from the land settles in the lee of protecting 

 cuspate bars. Two such bars penetrate into the lake 

 from the north and south shores and constrict the lake 

 west of the Deep Hole. The constriction is further 

 accentuated by a sandy shoal area extending north and 

 south across the lake and dividing it into two basins. 

 Except for this sandy shoal the entire bottom within 

 the 20 -meter contour is of clay mud. Two interesting 

 black mud areas of considerable size are located east 

 and west of Rondeau on the Canadian side. The larger 

 of these is approximately 45 miles long and has a 

 maximum width of 15 miles. 



173 



