Ordovician graptolites left fossils behind at a location 100 miles north of Lake Memphremagog .
The quality of these remains is usually so low that specimens worthy of collection are uncommon according to author Marian Murray .
Ordovician graptolites left fossils behind at a location 100 miles north of Lake Memphremagog but the quality of these remains is usually so low that specimens worthy of collection are uncommon according to author Marian Murray .