;j()8 Proceedings Portland Society Natural History 



weathering and erosion. The few hills which have been able 

 to withstand this denudation are prominent features of the 

 landscape. The Camden Hills and Blue Hill on the main- 

 land and the island of Isle au Haut are the more notable 

 of these residual mountains or monadnocks. The exposed 

 outer shores of the region are usually rocky and abrupt, 

 often with sea cliffs and headlands, while in the more pro- 

 tected localities, beaches, mud flats and salt marshes occur. 

 The water courses of the area are very insignificant, the 

 Megunticook River in Camden and the Ducktrap River in 

 Lincolnville alone justifying the name. Several so-called 

 rivers, such as the Bagaduce and Weskeag, are in reality 

 tidal estuaries. Lakes and ponds are fairly abundant, and 

 are usually morainal in nature, although scoop lakes and 

 barrier beach ponds are not uncommon. 



The soils of the region are very meagre and often entire- 

 ly lacking, especially at the higher elevations. They con- 

 sist almost entirely of formations of glacial origin. Glacial 

 till is everywhere abundant and well developed plains of out- 

 wash sands and gravels of glacio-fluviatile origin occur 

 along the outlet of Megunticook Lake in Camden and Oys- 

 ter River Pond in Rockport. A few kames are to be found 

 at Sandy Point in Stockton Springs. Marine clay is the 

 characteristic soil of the lowlands, together with a few post- 

 glacial deposits, such as beach sands and gravels or swamp 

 muck and peat. 



The rock structure still controls the topography of the 

 region, owing to the paucity of the soil. These underlying 

 rocks are predominantly silicious and acidic in nature. 

 Granite is the most widely distributed rock, occupying fully 

 one-half the entire area, and various micaceous schists and 

 quartzites are of frequent occurrence. Limestones are well 

 developed in the vicinity of Rockland and on Islesboro, but 

 they are not typical. The Islesboro limestone is very im- 

 pure, owing to the presence of many thin silicious layers, 

 and is rated as "too silicious for commercial use". Of the 



