38 PROCEEDINGS OF THE ASSOCIATION OF 



Dr. H. conceives these to be veins of sublimation, or in other 

 words, to be simple fissures filled from below by the metal in a 

 vaporous state, and that all the compounds had their origin from 

 cojoper in a native form. The conglomerate was stated to have 

 been noticed where the cement consisted to a large extent of ores 

 of copper, and even of copper in a native state. This was observed 

 only in close proximity to considerable veins. 



The veins, as well as different portions of the same vein, are very 

 variable in their metalliferous character, portions being apparently 

 rich, while others are completely barren. With the present knowl- 

 edge upon the subject, we can scarcely arrive at safe conclusions 

 as to the value of these veins for the purposes of mining, but upon 

 the whole they may be looked upon favorably rather than other- 

 wise. 



Adjourned to 4 o'clock this afternoon. 



Friday^ 4 o'clock, p. m. — Prof. Silliman being absent, Dr. 

 Locke was called to the chair. 



Dr. Jackson gave his views in relation to the construction of 

 geological maps, suggesting the importance of concert and uni- 

 formity in design and execution, as regards scale, coloring, sym- 

 bols, &c. on the part of the various state geologists employed 

 throughout the Union. The subject was further discussed by 

 Dr. Locke and Prof. Johnson, who concurred in the views of 

 Dr. Jackson. 



On motion of Prof. Mather, the subject was refen-ed to a 

 committee consisting of Dr. Jackson, Dr. Locke, and Prof. 

 Mather, who are to report at the next annual session of the 

 Association. 



Prof. Johnson exhibited a section drawn across the Frostburg 

 coal basin, extending bet^veen the Little Alleghany and Savage 

 Mountains, a distance of about four miles. He oflered some 

 observations concerning this coal-field, and enlarged upon its 

 value and importance as a coal and iron region. 



Mr. Hodge and Mr. Trego, who had explored that portion of 

 this basin which extends into Pennsylvania, also made some re- 

 marks in which they differed from the views of Prof. Johnson ; 

 particularly with regard to his opinion that some of the upper 

 strata of the carboniferous rocks near the Savage Mountain, rest 

 unconformably upon the lower ones. 



Mr. HoDoE placed on the table some clay concretions from 

 Kennebec river. 



On motion of Dr. Beck, Resolved, Thai when this Associa- 

 tion terminates its present session, it adjourn to meet in Boston, 

 on the last Monday in April next. 



