SOIL OF SALT MARSHES. 243 



differ also here and there in regcard to the relative proportion 

 of sand, and of clayish silt. The admixture of sand renders 

 the clayish silt permeable, and thus fit for successful drainage. 

 The degree of fitness in that respect depends on the relative 

 proportion in which they constitute the soil. There are evi- 

 dently unusual differences in regard to that point ; for whilst 

 the soil in some cases, in conseauence of the size and the 

 quantity of the sand, proves to be very favorable for drainage, 

 in other instances, on account of opposite conditions, it 

 becomes very impervious to water. 



The existence of a layer of that kind in close proximity to 

 the surface-growth, particularly in case the locality is some- 

 what depressed as compared with the surrounding level of the 

 soil, and thereby favors the accumulation of the drainage 

 waters of the surface-layers in its vicinity, causes, quite 

 frequently, barren spots in the midst of a healthy new vegeta- 

 tion. 



The rain water, after having abstracted more or less of the 

 residual saline matter of the salt water which formerly over- 

 flowed the marshes, collects usually in more or less large 

 quantities in these depressions, where it may evaporate at any 

 time during the season in consequence of an inefficient drain- 

 age, leaving the saline constituents behind. Althouijh these 

 washings of the surface-soil in their diluted state may not 

 affect the new growth in the early spring, they will surely 

 prove highly injurious to most of our farm plants as soon as 

 they reach a high degree of concentration by evaporation. 



Localities which sufter from these influences are quite 

 frequently covered during the first part of the season with a 

 new, valuable vegetation, similar to that of the surrounding 

 lauds ; yet become barren as soon as the natural rate of 

 evaporation of water exceeds the access of the latter by 

 atmospheric precipitations. 



These spots appear, in the latter part of the season, as 

 if the torch had passed over them, for nothing but a few 

 genuine salt-plants are usually left. 



As the final result in these cases is quite naturally a matter 

 of degree, every stage of injurious reaction may be noticed. 

 A close examination of the dry surface mass within these 

 depressions revealed the presence of common salt, with some 



