642 



SCIENCE 



[N. S. Vol. XXVI. No. 671 



western corner of the Coastal Plain in western 

 Cumberland, Moore, Rich^jond and Scotland 

 counties, where the coastal plain materials lie 

 at greater elevations, would disclose well-de- 

 veloped terraces at these and greater eleva- 

 tions. 



■ Conclusions. — In a short paper like the 

 present it is impossible to go into details 

 regarding the origin of these terraces. The 

 present topography of the North Carolina 

 coastal plain appears to be due to the succes- 

 sive formation, with the uplift of the coast, of 

 the three sandy ridges described above, the 

 latest of which is represented by the present 

 banks or bars enclosing Pamlico, Albemarle 

 and Currituck sounds, and the formation of 

 the several terraces within the areas thus 

 enclosed. 



The marked difference in elevation of the 

 coast in the northern and southern parts of 

 the ceastal plain of this state is due to the 

 fact that the lowest Jying terrace borders the 

 coast from Bogue Inlet north while to the 

 south the next higher terrace fronts on the 

 shore. 



Terraces at these same elevations appear on 

 topographic maps in Virginia and Maryland. 



B. L. Johnson 



U. S. Geological Subvey 



PLANT ZONES IN THE ROCKY MOUNTAINS OF 

 , COLORADO 



In order to see the true relations of the 

 flora of a mountain region some sort of classi- 

 fication into zones is necessary. - Humboldt 

 and later other students have pointed out the 

 zonation on mountain sides and the zones 

 have been delimited with greater or less ac- 

 curacy. In order to call attention of my stu- 

 dents to "the zonation in our own Rocky Moun- 

 tains I have prepared a classification which is 

 proving useful for teaching purposes. It em- 

 phasizes to the student the various climatic 

 and edaphic influences which accompany 

 changes in altitude. 



Schimper's three regions of mountains,' the 

 hasal, the montane and the alpine, are not 



' Schimper, " Plant Geography" (English trans- 

 lation), p. 702, 1903. 



exactly represented in the Rocky Mountains. 

 Thus the basal region of Schimper is " like 

 that of moist stations in the lowlands." In 

 the Rocky Mountains there is no such basal 

 region. In fact there are no true lowlands 

 near the mountains to be used for comparison 

 and the foothill plants are not like those of 

 gulch and stream-side in the plains region. 

 Schimper's montane region has a flora " re- 

 sembling that of the lowlands in higher lati- 

 tudes." In northern Colorado this zone would 

 extend from about 8,000 to 10,000 feet in alti- 

 tude. Here the general character of the vege- 

 tation reminds one of the northern parts of 

 New England, Michigan, Wisconsin and Min- 

 nesota. Above 10,000 feet I believe it more 

 conducive to clearness to make two zones — an 

 alpine and a sub-alpine — the former including 

 everything above " timber line." 



The following classification of the zones of 

 plant life is suggested as pointing out what 

 the limits of the zones seem to be. I am by 

 no ' means sure that the names used are the 

 best which might be selected. The zones here 

 indicated are those recognized along the east- 

 ern slope of the Rocky Mountains, especially 

 in northern Colorado. The names and char- 

 acterizations are offered in the hope that they 

 may call forth criticism from other students 

 of Rocky Mountain vegetation. 



1. Plains Zone. — Altitude up to about 5,800 

 feet. This is a grassland formation, the 

 grasses interspersed with and sometimes dis- 

 placed by coarse composites. Trees and shrubs 

 occur only along water courses or on rock 

 rfdges and buttes. 



2. Foothill Zone.— Altitude 5,800 to 8,000 

 feet. This is generally a rather open forest 

 of rock pine (Pinus scopulorum) on hillsides 

 with a few scattered cedars {Sahium scopiv- 

 lorum), while there is a mixture of Douglas 

 spruce (Pseudotsuga mucronata) on north 

 slopes with some deciduous trees in the can- 

 yons and draws. 



3. Montane Zone.— Altitude 8,000 to 10,000 

 feet. This is a closer forest than that of the 

 preceding zone. Lodgepole pine (Pinus mur- 

 rayana) is the dominant forest tree, frequent- 

 ly forming dense, pure forests. Rock pine 



I 



