Rock Tripes on a Long Island glacial boulder 



Raymond H. Torrey 



An occurrence of lichens which stimulates speculation as to 

 its origin is a large colony of two forms of Rock Tripe, on an 

 immense glacial boulder, near Wading River, Suffolk County, 

 Long Island. This boulder, known locally as the Split Rock, is 

 one of the largest in the long list of really big boulders in Fuller's 

 Geology of Long Island. It is a mass of reddish gray granite, 

 probably from eastern Connecticut, and was originally about 

 20X20X30 feet but is split into several large fragments. It is on 

 a lobe of the Harbor Hill Moraine, about half a mile north of the 

 highway at a point three quarters of a mile west of Wading 

 River. Mr. W. T. Davis, of the Staten Island Institute of Arts 

 and Sciences told me of the lichen colony, from recollections of 

 years ago, and I visited it recently. 



Three of the fragments bear dense colonies of the Smooth 

 Rock Tripe, Gyrophora Dillenii, and the blistered form, Um- 

 bilicaria pustulata, mixed with each other. I have not seen 

 these large foliose lichens on any other glacial boulder on the 

 island, but will search others. Earth and bark lichens are quite 

 plentiful on eastern Long Island, where fires have not been too 

 severe, but these Rock Tripes, which are familiar to the most 

 casual observer, in the highlands of New Jersey and southern 

 New York, and are also common on ledges on the Connecticut 

 side of the Sound, are rare on Long Island, where the only rocks 

 on the surface are glacial boulders. 



This part of Long Island was covered with ice when the 

 Ronkonkoma Moraine, to the south, was laid down; and was at 

 the front of the ice when the Harbor Hill moraine was formed. 

 Vegetation has since migrated in. The variety and numbers of 

 earth lichens, such as Cladoniae, and various bark and some 

 rock lichens, on small and large boulders, such as Parmelias, 

 and Physcias in Suffolk County, suggest that these species had 

 relatively little difficulty in establishing themselves, in spite of 

 their dependence on associated algae. But these Rock tripes 

 ordinarily like plenty of room; the bigger the boulder or ledge, 

 in their habitats in the Highlands, the better they grow. It is 

 probable that there are not many boulders big enough, or suffi- 

 ciently exposed in the glacial moraines or outwash, or far enough 



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