CHAPTER I. 
RESUME 
OF A GEOLOGICAL RECONNAISSANCE EXTENDING FROM NAPOLEON , AT THE JLNCTION OF THE ARKANSAS 
WITH THF MISSISSIPPI, TO THE PUEBLO DE LOS ANGELES IN CALIFORNIA. 
(Extract from Report of Ejcplorations for a railway route ^ near the thirty-fifth parallel of latitude , from the Mississippi 
river to Ike Pacific Ocean; by Lieutenant, now Captain A. W. Whipple, corps of Topographical Engineers. 
Chapter VI.; page 40 etc.; Washington, 1855. House of Representatives, Documents N. 120.) 
Dear Sir, 
Boston, July 26*’* 1854. 
In obedience to the instructions contained in your letter of the 2‘' July, dated Washington 
city, District of Columbia, I have the honour to send you the R^sumd of the geological reconnais- 
sance that I made in connexion with your survey for a railway route near the Thirty-fifth parallel 
of latitude, from the Mississippi river to the Pacific Ocean, extending from Napoleon, Arkansas, 
to the Pueblo de los Angeles in California. 
Having in my possession, as yet, neither the specimens which 1 collected, nor a good map 
of the country passed through , and the time being very short which is left me to make my report , 
I trust you will excuse the brevity of this Resume-, in which, however, I will endeavour to show 
the principal geological results of my exploration, in order to give a general idea of the minera- 
logical resources of the route with regard to the construction of a railroad. 
Napoleon is situated on the Alluvium of the Mississippi, which extends on the two banks of the river 
Arkansas as far as Little-Rock, and is composed of a very fine-grained, reddish-yellow earth. 
This alluvial deposit forms the richest agricultural portion of the State of Arkansas , and as it con- 
stitutes the whole of the basin which extends from Little-Rock to the Mississippi, and is always 
in horizontal beds, these rocks, it will be seen, offer no obstacle to the construction of a railroad. 
At Little-Rock the Alluvium is replaced by rocks, forming a line of mountains, whose direc- 
tion is from west-west-south to east-east-north. These rocks continue for three or four miles 
along the river , and are formed of black slates , of gray quartzose metamorphic masses , traversed 
by veins of white quartz , having the same direction as the mountains. 
On the left bank of the Arkansas, two miles higher than Little-Rock, the sandstones and lime- 
stones of the Carboniferous -period begin to appear, resting horizontally upon the metamorphic rocks. 
Here begins the line coal-basin of Arkansas, which is only a continuation of the immense coal- 
field of Iowa, Missouri, Kansas, and which extends even to Fort Relknap,. Rio Brazos, and to 
the Rio San Saba, Texas. Our survey has traversed this basin from the vicinity of Little-Rock 
to Delaware mount, a distance of more than four hundred miles; coal being found almost every- 
where from Petit-Jean mountain to Coal creek and the Shawnee mountains. It forms a vast re- 
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