7.0 
6.0 
0C 
< 
UJ 
> 
5.0 
O' 
* 
E 
O' 
s 
CL 
Q 
O 
CO 
CO 
4.0 
3.0 
2.0 
1.0 
BACK RIVER 
MIDDLE RIVER 
1780 
1800 1820 1840 I860 1880 1900 
TIME IN YEARS 
1920 
1940 
I960 
1980 
Figure 5 
Comparison of sedimentary chlorophyll degradation products 
in Back and Middle Rivers (from Brush unpublished). 
Figure 6. Zinc concentrations in dated cores from Chesapeake Bay 
(from EPA, 1983). 
27 
