286 The Mesozoic Sandstone of the Atlantic Slope. [ May, 
northern part of the Richmond belt [?]), whose uppermost beds 
pass into the lowermost of the Petersburg belt; and finally a 
seventh belt C 1 or the Fredericksburg belt. The area (or areas) 
covered by Mesozoic near Hicksford, which constitute the por- 
tions of Mr. Heinrich’s A 2, Prof. Fontaine does not name, as he 
acknowledges that he has not visited them. 
Mr. Heinrich’s lucid and careful observation of the rocks 
which follow that of the boundaries of his belts, cannot be too 
highly commended. They are classed as 1, Conglomerates; 2, 
Sandstones, (a) Psephites or Siliceous and Feldspathic, and (6) 
Psammites or argillaceous matter with fine siliceous sand and 
some larger grains of quartz; 3, Slates and Shales; 4, Lime- 
stones; 5, Coal, (æ) bituminous, (4) carbonite, (c) natural coke, (d) 
semi-anthracite ; 6, igneous rocks; 7, accessory minerals. 
The following six pages are devoted to a very good sketch of 
the general geological and stratigraphical characters of the forma- 
tion, consisting of some useful information as to areas of 
drainage. 
This third division of his subject ends with a succinct descrip- 
tion of the results of diamond-drill boring, and the separation of 
the measures pierced, into seven groups. This is an exceedingly 
interesting portion of the paper, each division is so clearly dis- 
tinguished from the others by striking characteristics as to seize 
the attention of the reader, who is too apt to forget that he sees 
so clearly because he is looking through Mr. Heinrich’s eyes. 
The next six pages are given up to a detailed lithological 
description of the section by inches. The third chapter closes 
with a summary of the results of investigation, and an observa- 
tion (confirmed by the study of the measures near Dillsburg, Pa.) 
that the largest beds of trap, more frequently followed planes of 
bedding than planes of cleavage. 
The fourth division of his subject is devoted to the fossil 
remains of the formation, but here Mr. Heinrich confesses his 
inability to do justice to the subject, and Prof. Fontaine’s informa- 
tion is fuller and has the additional advantage of his own excellent 
critical judgment, at least so far as concerns the flora. 
The fifth and last division of Mr. Heinrich’s report regards the 
economical products of the formation, prominent among which, 
of course, is the coal. Forty-nine analyses are given on p. 42, 
1 Frazer’s Report. CC, Sec. Geol. Surv. of Penna. 
