Crosby.] 
118 
[May 21, 
a good section of the undisturbed till. Sixteen samples in all were 
examined, from twelve different drumlins ; several from the super- 
ficial, oxidized or buff colored till, but the majority from the great- 
est accessible depth in the bluish-gray, unoxidized till, the true 
liard-pan. On some of the drumlins, including especially the large 
East Boston drumlin, and Convent Hill, in Somerville, the super- 
ficial weathering or oxidation of the till is more marked and deeper 
and its lower border more sharply defined than usual ; and in these 
cases one sample was collected from each division of the till ; while 
in the case of the Milton Hill and Ten Hill Farm drumlins the 
sections were not deep enough to expose the lower till, and the 
upper till alone was collected. The subjoined numbered list of 
the samples follows the order in which the analyses were made, 
without regard to the geographical distribution of the drumlins : — 
1. Buff till from the small drumlin near Mount Hope station, on 
the Boston and Providence R. R., about eight feet below the sur- 
face. 
2. Gray till from the Skinner Hill drumlin, about one-eighth of a 
mile east of Roslindale station, on the north bank of the railway 
cut and fifteen feet below the surface. 
3. Gray till from the northwest end of the Parker Hill drumlin, 
about twenty -five feet below the surface. 
4. Buff till from ditto, ten feet below the surface. 
5. Gray till from the large drumlin forming the northwest part 
of East Boston, about twelve feet below the surface and six feet 
below the sharply defined border of the buff till. 
6. Buff till from ditto, three feet from surface and directly above 
No. 5. 
7. Buff till from the northern base of the Milton Hill drumlin, 
near the Neponset river and three feet from the surface. 
8. Gray till from the northwest end of the Convent Hill drum- 
lin, in Somerville, about seven feet below the bottom of the buff till 
and nearly twenty-five feet below the surface. 
9. Buff till from ditto, eight feet below the surface. 
10. Gray till from the railway cut in the Mt. Bowdoin, drum- 
lin, in Dorchester, twenty-five feet from the surface. 
11. Buff till from ditto, six feet from the surface. 
12. Buff till from the northern base of the Ten Hill Farm drum- 
lin, in Somerville, about seven leet below the surface. 
13. Grajr till fromthe northwest end of the Green Hill drumlin, 
