Review of decent Geological Literature. 359 
the encroaching plants, which grow with the most vigor near its banks. 
Because these channels obstructed the harvesting of the hay crop, nearly 
all the sea-coast swamps of New England have been ditched so that the 
tide now finds it entrance and egress by a system of artficial parallel 
channels a few rods apart; and in consequence the natural water-courses 
have often disappeared, their beds being rapidly filled by mud and the 
rank marsh vegetation. 
Professor Shaler states that the aggregate area of salt-marsh lands 
•capable of being reclaimed from the sea by dikes and brought under 
cultivation exceeds 200,000 acres for that portion of the Atlantic coast 
lying between Portland and New York. The present agricultural value 
of these lands for their product of hay does not exceed about $10 per acre : 
but under cviltivation like the similar lands gained from the sea in Holland 
.and other northern parts of Europe they will have a value of not less 
than $200 per acre, amounting in total to at least $40,000,000, and it is 
•estimated that the cost of reclaiming these acres and reducing them to 
cultivation should not exceed the fifth of this sum. They are unsurpassed 
in fertility as market-garden soils and are practically inexhaustible. 
South of the New England shore the marsh area is much more extensive 
than in that region, and it is probable that the improvable marshes of our 
■ entire eastern coast amount to at least 3,000,000 acres. 
The limited tracts of sea-coast swamps are described in detail, with 
maps, namely, the Plum Island marshes which extend Southward from 
the north of the Merrimac river, and the diked lands of Green Harbor 
river in Marshfield, Mass. A catalogue of the .salt marshes on the coast 
-of New England south from Casco bay and of Long Island is also given, 
with their approximate areas derived from measurement on the Coast 
Survey charts. 
Postglacial marine deposits containing shells of the Leda, with other 
genera that inhabit the northern circumpolar seas and extend south to 
temperate latitudes, occur in Maine up to 200 feet or more above the 
present sea-level, showing that at the close of the glacial period the ocean 
there covered more of the land than now. It therefore seems very re- 
markable that no evidence of elevated marshes or beaches has been found 
in that region; and their absence proves that this northward postglacial 
submergence was very brief, and that the sea very ciuickl}' attained its 
present altitude, pausing at no time long enough to develop the charac- 
teristic features of a shore line. 
On nepheline rocks in Brazil, with special reference to the. association of 
fhonolite and foyaite. By ORViLLE A. DERBY. (From the Quart. Jour. 
Geol. Soc. London, August, 1887). The author gives descriptions of 
the field-appearances of the rock masses of foyayte and phonolyte. He 
■ concludes that these indicate (i) the substantial identity, as regards mode 
of occurrence and geological age of the Caldas phonolytes; and foj'aytes 
■ (2) the connection of the latter, through the phonolytes, with a typical vol- 
canic series containing both deep-seated and aerial types of deposits ; (3) the 
-equal if not greater, antiquity of the leucite rocks as compared with the 
