138 GEOLOGICAL RECONNOISSANCE 
thence diverging to the south, it reaches the Indian boundary line, in the 
south-west corner of that county. 
Its southern limits cannot yet be defined, since this formation extends 
south of the Arkansas river, beyond the range of our, present geological 
reconnoissance. 
All the accessible veins and deposits of lead, zinc, and manganese ores, 
at present known, are situated to the north of this line; they doubtless 
extend beneath a portion of the area occupied by the millstone grit; but, 
probably, are too deeply seated in the midst of the high mountainous dis- 
trict, south of this line, to be reached by the miner, except near the valley 
of the Arkansas river in Pulaski county. 
The coal beds interstratified amongst the beds of the millstone grit, are 
too thin to be worked profitably by drifts. 
Where the porous sandstones of the millstone grit form synclinal troughs 
under the drainage of the country, there are favorable positions for reach- 
ing productive brines by boring. Several of these saline troughs seem to 
exist, six to twelve miles north of the Arkansas river, in Crawford, Frank- 
lin, Johnson, and Conway counties. 
Large quantities of iron are disseminated amongst the beds of the mill- 
stone grit’; when associated with the sandstones of that formation, it: is 
generally too sandy to be smelted with profit and advantage ; but the under- 
lying ferruginous shale in many places offers encouragement for the search 
of the iron manufacturer, as for instance, at the Dwight Old Mission, in 
Pope county ; on War Eagle, in Madison county; and the centre of Wash- 
ington county. The bog iron ore of Pulaski county, 8 miles north-east of 
Little Rock, promises to be sufficiently extensive to supply a furnace, ac- 
cording to the report of the Assistant Geologist. 
The time allotted for working up and reporting on the materials which 
have been collected during the field work of this and the preceding season, 
has been too short to admit of the full digest, due consideration, and minute 
analysis of all the subjects and specimens now on record, and in the office 
of the Arkansas survey; we have, in fact, only been able to make a com- 
mencement towards a thorough investigation of even the resources now 
within our reach. If the means are provided, we hope, hereafter tobe able 
to complete this important, interesting, and useful work, begun under such 
favorable auspices. , : 
If the survey is continued, it would be desirable to put at least three 
corps in the field, in order to carry forward the work as rapidly as possi- 
ble. For that purpose, the geological appropriation should be equal to 
that in Missouri; that is, twelve thousand dollars ($12,000) per annum. 
