ALBION MORAINE. 707 



arch and dip at various angles. They, however, show a tendency to slope 

 with the surface irom the crest toward each side of the ridge. A surprising 

 feature in these gravel pits is the very large percentage of Medina sandstone 

 fragments. By actual count they constitute about 90 per cent of the pebbles. 

 The sand also must contain a large amount of rock fragments of the same 

 formation, for it has the pink tinge characteristic of the sandstone and shales. 

 The till of this moraine occasionally presents a pink tinge because of 

 the presence of the Medina shales, but ordinarily it has a blue cast and the 

 coarse fragments seem to consist more largely of limestone than of sandstone. 

 The granitic and other crystalline rocks of distant derivation do not consti- 

 tute a prominent part of the till, but are very abundant on the surface. 



RELATION TO LAKE WARREN. 



Until this moraine has been traced farther east its relations to Lake 

 Warren can only be conjectured. It was probably formed near the close 

 of the existence of that lake, for the waters must have fallen to a lower level 

 as soon as the ice sheet uncovered the Mohawk outlet. Possibly the outlet 

 was opened aud the lake level lowered before the moraine was formed. 



INNER BORDER PHENOMENA. 



Between the Albion iuoraine and Lake Ontario there is a plain sloping 

 gradually toward the lake, as may be seen by PI. III. It is traversed 

 by the Iroquois beach, which lies 1 to 4 miles north from the inner border 

 of the moraine, from the Genesee westward to Oak Orchard Creek. Above 

 the level of this beach drift swells are not uncommon, but below it they are 

 very rare. There are, however, just west of the mouth of the Grenesee, a 

 few small drumlins, standing only 50 to 75 feet above the level of Lake 

 Ontario, or more than 100 feet below the level of the Iroquois beach. 



The drift is usually thin throughout this plain, a depth of 50 feet being- 

 rare. It has been noted by Grilbert ^ that the divides between the drainage 

 lines usually carry a smaller amount of di-ift than the sags tlu-ough which 

 the streams have their courses. This, as Gilbert announced, is a matter of 

 some significance, in that it shows that the drainage is not controlled by 

 ridges of drift, but instead by furrows in the rock. He considers these 

 furrows immense glacial groves, as indicated more fully below (p. 709). 



' Bull. Geol. Soc. America, Vol. X, 1899, pp. 126-129. 



