ST. JOHN: SABLE ISLAND. 41 
Sand Dunes. — If one may be allowed to generalize, the whole 
island is only a series of undulating sand dunes. All of them are in a 
continuous state of flux, but at any one time they can all be placed 
into one of several categories. A strong sea breeze blowing at low 
tide will pick up grain after grain of sand from the dry upper half of 
the beach, and transfer it inland. A storm wind, while doing the 
same thing, will often make a breach in the outer side of the most ex- 
posed dune, whirl away the sand from the roots of the protecting 
vegetation, and soon form a deep gully from which the sand is swirl- 
ed inland without obstruction. Coming from either of these sources, 
the sand is blown inland, then dumped in a quiet place. Whatever 
happens to be beneath, pond, cranberry-bog, or Life Saving Station, 
is buried by the new dune. These most recently formed dunes are to 
be met with all over the island, and are, of course, without vegetation. 
During the growing season the plants near by will tend to colonize 
them and, unless the boisterous winds keep them in constant motion, 
young plants will come up on them and tend to hold them in place. 
The first to appear in such situations is the Beach Grass, Ammophila 
brcviligulata^ Fernald. Soon after, Lathyrus maritimus (L.) Bigel. 
and Solidago sempervirens L. appear. If other storms do not inter- 
fere by shifting the dune to still another place, these plants will spread, 
and before long the dune will be fairly covered with vegetation and 
anchored by roots. Other species will creep in and join these three 
dominant ones, and soon the dune has on it many species such as Des- 
champsia flexuosa (L.) Trin., Frstuca rubra L., Smilacina steUata 
(L.) Desf., Fragaria v'lrginiana Duchesne, var. terrae^novae (Rydb.) 
Fernald & Wiegand, Rosa virghiiana Mill., Convolvulus sepium L., 
and Anaphalis margaritacea (L.) B. & H., var. subalpina Gray. On 
the protected slopes of the more permanent dunes these species, es- 
pecially the Rose, the Bcacli Pea, and the jNIorning Glory, form a 
tangle that is waist-high and very difficult to penetrate. 
Empetrum Heaths. — These are in reality the ultimate stage in 
the evolution of the sand dune. They are fountl in the middle of the 
broadest part of the island, the place most protected from the erod- 
ing elements. The dunes themselves are low and undulating, and 
covering them is a low vegetation, composed especially of the trail- 
ing branches of Empetrum nigrum L., Juiiiprrus communis L.. \ar. 
megistocarpa Fernald & St. John, and Junipcrus horizontal is Moench. 
Together they form a green, springy carpet nearly a foot in thick- 
ness. ]\Ii.\e(l with the doiuinant species are, of course others, such 
