J. D, Dana on the Plan of Development, &c. 335 
Art. XXV.—On the Plan of Development in the Geological His- 
tory of North America, with a map; by James D. Dana. 
On other occasions, I have discussed at some length, the out- 
line and_ surface features of the continents, the parallel courses 
aracter- 
istics of our globe.* I propose at this time to point out the rela- 
tions between the operations of this principle or agency and the 
special geological history of the North American continent. 
To render this application of the subject intelligible, it is ne- 
cessary to review briefly the fundamental facts just alluded to. 
For this purpose, I would direct attention to a Mercator’s Chart 
of the World, (sce plate) on which the whole is open to exami- 
nation—such a chart being a minature representation of the facts 
themselves, and the order observed among its parts, the syllables 
which spell out the principles. 
In the first place, note the two great oceans, the Alantic and 
the Pacific—both widening south, and coalescing in a vast ring 
of ocean around the south pole, while narrowing north and uni- 
ting ina small arctic sea. The Indian Ocean isa third north 
and south ocean: but it reaches north only a little ways beyond 
the equator. 
As the Atlantic is less than half the breadth of the Pacific, so 
Sented by the line M M), 
trend of the Atlantic ( meter, 
Corresponds with the general trend of the Pacific islands; for 
these islands have a nearly parallel course all through the ocean, 
the New Hebrides, Kingsmills, Samoan, Tahitian, Marquesas 
and Sandwich islands, lying in approximately parallel lines.t 
: eol. . Ex- 
ao ok is vol. te 
Red. 756 pp. 4to, 1849, pp. 11, 4 d 
Meeting, 1 d page 30 volume. 
+ I may here add, what I have elsewhere explained at length, that the trends of 
a hil ing a rrespondence of directi to “0% 
the i her the A e Pacifi 
it the Paumo merpctah ame ie ar atill farther east, in Easter Island and Gomez 
is thence continued on a west-northwest course, by the Society Islands, and the Her- 
vey Islands more south; thence by the Samoan and Fakaafo groups; thence more 
northwesterly by the Vaitupu snd Kingemills, to the Radack and Ralick groups, 
