harbor entrance, delineating a ridgelike formation which extends obliquely 
lakeward from north to south. Deeper contours to the southwest of this forma- 
tion suggest that it may extend as deep as 50 feet. The ridge has a maximum 
height of approximately 7 feet, and occurs due west of the harbor entrance. 
Between the ridge and the harbor entrance is a steep trough about 34 feet deep. 
A lack of survey data before the harbor construction prevents a reliable con- 
clusion as to whether or not this underwater ridge was caused by the presence 
of the breakwaters. However, the possibility cannot be ruled out that it was 
formed by the littoral drift arriving predominantly from the north and flushed 
lakeward by the breakwater. This material, unable to return shoreward due to 
the absence of significant swell activity in this region, could have accumulated 
to form such a formation on the offshore bed over a long period. Implications 
of this interpretation are significant because it may mean that little, if any, 
bypassing material across the harbor entrance could be expected to reach the 
southern shore of Holland Harbor. 
Many of the dunes reach a height of 150 feet, and in a few places exceed 
200 feet above the lake level. The highest dunes are confined to a belt about 
1 mile wide but lower ones occur for a width of several miles near Holland. 
Dune building by wind action is still active. North of Holland Harbor some 
low dunes are actively migrating inland or leeward from the bluff onto rela- 
tively level upland. In this area the dunes are 40 to 120 feet high. At nu- 
merous places, slumping of vegetation is evident on the bluff slopes. South 
of Holland the dunes are higher, frequently more than 200 feet above lake level. 
The dunes are well vegetated except for occasional blowouts on larger dunes. 
At many places, dunes descend directly to the lake or to a narrow strip of 
beach up to approximately 50 feet in width. The only area near Holland Harbor 
where a substantial beach exists is about 2,000 feet immediately north and about 
500 feet immediately south of the breakwaters. Maximum beach width in this area 
is about 500 feet on the north side and 150 feet on the south side, indicating 
the predominance of littoral drift from the north. Berm development is gener- 
ally poor for many miles of shoreline north of Holland. Berms develop more fre- 
quently south of Holland, growing to an average height of 1 foot in the swash 
zone. These berms are usually truncated at positions of a recessed shoreline 
where a rip current has gouged a deep channel across the surf zone. 
3. Littoral Materials. 
The dominant littoral material which comprises dunes, beaches, and nearshore 
lake bottom is glacial sediment belonging to a fine sand category (less than 
0.42 millimeter in median diameter). Scattered pebbles are found both on the 
dunes and the lake bottom. Sand-sized material is dominantly quartz {80 to 85 
percent) with up to 12 to 15 percent feldspar. Heavy materials represent only 
ZEON Se PeXcenit. 
a. North of Holland Harbor. An analysis of bluff, foreshore (above low 
water datum) and bottom samples indicates that the majority of these sands 
belong to the fine sand category. (The Unified Soil Classification System 
defines fine sand as ranging in size from 0.42 to 0.074 millimeter (1.25 to 
3.75 phi), and medium sand as ranging from 0.42 to 2.0 millimeters or 1.25 to 
-1.00 phi). North of the harbor, the average bluff and foreshore sand consists 
of 88.0 percent fine sand and 11.7 percent medium sand; the average lake bottom 
sand consists of 95.0 percent fine sand and 5.0 percent medium sand. A general 
38 
