3. Lor ain-Vermil ion . 



a. Bathymetry and Bottom Sediment . The southern part of the Lorain- 

 Vermilion sand deposit forms part of an elongate bathymetric high whose southern 

 limit lies about 9.5 kilometers north of the towns of Lorain and Vermilion, Ohio 

 (Fig. 12). The bathjnnetric high rises from -14.5 meters and can be divided into 

 two elevated areas, one more prominent within the study area than the other, 

 separated by a shallow trough oriented northwest-southeast (Fig. 15). The prom- 

 inent high has a "bootlike" shape and is characterized by a 2-kilometer-long 

 ridge on its southern part, similar in morphology to the Presque Isle sand de- 

 posit described by Williams and Meisburger (in preparation, 1980). The remain- 

 der of this high consists of a more subdued ridge or series of ridges which 

 becomes narrower and more distinct to the north. The other, less prominent high 

 within the study area is the southern end of a broad high which extends north- 

 westward across the lake and joins the Canadian shore at Point Pelee, Ontario. 



Surficlal sediments on the Lorain-Vermilion bathymetric high are almost ex- 

 clusively sand and gravel (Fig. 16). The transition from sand to mud is fairly 

 abrupt on the west and south sides of the sand area; in contrast there is a 

 gradual transition from sand to mud on the east side. Till is exposed in places 

 in the northern part of the sand area. Overall, the surficlal sand shows a 

 lateral gradation in sediment size from gravel on the west to very fine sand on 

 the east (this same trend was noted by Hartley, 1960) . Hartley estimated the 

 composition of the sand using a binocular microscope to be 70 to 80 percent 

 quartz and feldspar . "Shale makes up most of the remainder with fairly abundant 

 heavy minerals. . . . Limestone is common in the sand though it usually comprises 

 less than 10 percent . Shells are locally very abundant and may make up as much 

 as 25 percent of a sand sample." (Hartley, 1960.) 



b. Subbottom Sediment and Sand Volumes . The eight cores taken in this area 

 contain well-sorted, fine to coarse sand ranging in thickness from 0.8 to 4 

 meters. Sand overlies till on the bathymetric high, but caps finer postglacial 

 sediments In the surrounding areas. The sand on the eastern flank of the high 

 has a higher content of silt and clay. Southwest from the high the sand In- 

 creases in thickness to where the thickest sand accumulation (4 meters) is found 

 in core 90 (Fig. 16). This part of the deposit consists of medium to coarse 

 sand with gravel overlying muddy sand which in turn overlies a clayey silt . To 

 the west of the bathymetric high the contact with the modern lacustrine mud is 

 sharp ; cores 95 and 96 contain several meters of mud overlying a gravelly clay 

 till. The sequence of mud over till is also common south and east of the de- 

 posit, with the exception of cores 84 and 86 which contain about 3 and 0.5 

 meters, respectively, of muddy fine to medium sand over a till surface. The 

 extent of the deposit defined by cores 84 and 86 is not well known because of 

 limited data; the sand may represent a minor, localized deposit derived from 

 erosion of the main sand ridge. 



Sand volumes were computed for the thickest part of the sand deposit associ- 

 ated with the boot-shaped high using the areas and thicknesses of sand shown on 

 the isopach map (Fig. 17). (The "lag" Isopach line is taken to be a "0" thick- 

 ness of sand for computation of volume, but in reality sand does exist outside 

 this line; see Fig. 16.) The volume calculated is about 32 million cubic meters. 

 Hartley's (1960) Isopach map of the same area gives a similar volume, assuming 

 his 1-foot contour correlates with the lag contour in this report. 



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