122 'kevieiv of 'Recent Geological Literature. 
1 8 feet in thickness, witliout a break, and in North Wales there is a con- 
tinuous series 350 feet in thickness, without the intervention of lime- 
stones. 
[See editorial note on the Carboniferous chert of Iowa on another 
page of the present number of the Geologist.] 
Ainiiial rcfort of the department of mines, Nc-v South Wales. Bj Harrik 
Wood, Under Secretary of Mines. (A Government document of New 
South Wales, Sydney, 1S87.) This volume contains the administration 
and progress reports of the department, including those of the geological 
surve}', and statistics of all mining operations in the colony. Mr. C. S. 
Wilkinson, the geologist in charge, announces the discovery of fossils of 
the Triassic (thoracic plates of Alastodonsanriis) and of a large fossil 
shell, from the Hawksbury sandstone. The latter is figured and named 
bv Mr. Robert Etheridge, jun., Tremanotns maideni. It has a resem- 
blance to 'J'reinanofiis alfhcus Hall, from the Niagara group. 
Geology of the Vegetable creek tin-mining field, Ne-v England dis- 
trict, Neiv South Wales; quarto, tvith mafs and sections. By T. W. Edge- 
worth David. (A publication of the geological survey of New South 
Wales, Sydney ; C. S. Wilkinson, geological surveyor in charge.) The 
discovery of tin in New South Wales was first announced by Rev. W. 
B. Clarke, in 1S49. In 1885 the output of tin amounted to 2,505 tons. 
Continued prospecting of surface tin gravels led on by degrees to the 
disco\ery of the tin veins. The shallow workings produced their largest 
vield in 1881, since which time their productiveness has constantly de. 
clined. The "deep leads" which were first worked in 1883, now yield far 
more ore than the shallow gravels, and will probably continvie to form a 
valuable source of stream tin for many years to come. The tin veins 
have not yet been fairly tested, and it would be premature to predict 
their value and permanence. The age of the "deep leads" is regarded 
as early Tertiary, determined by fossil plants identified by Baron von 
Ettingshavisen. The age of the intrusive tin-bearing granites is thought 
to be Permian. No granites in the colony have appreciably disturbed 
the Triassic rocks, whereas there are intrusive granites newer than 
the Carboniferovis. The age of the granites is, however, not regarded 
as well established. Laterite is classed with basalt. It is found to be 
most largely developed near the highest points of the sheets of lava, but 
it varies in structure and composition, some specimens being more allied 
to a sedimentary formation than to a \olcanic. The paleozoic rocks are 
considered Upper Silurian. 
Preliminary paper on the driftless area of the upper Mississippi valley. 
By T. C. Chamberlin and R. U. Salisbury. Pages 190-322; plates 
xxiii-xxix. (Accompanying the sixth annual report of the director of 
the United States geological survey.) 
Under the thorough and fruitful discussions of this paper, the driftless 
area and its environs contribute much to our knowledge of the ice age, 
especially in regard to the preglacial topography and surface deposits, 
glacial planation and the average thickness of the drift, relative age of 
