176 



SCIENCE. 



[Vol. XX. No 503 



genealogies accompanied by portraits of pilhua =the heads 

 or founders of large families as found recorded in native 

 MSS. It is more probable that in a state of semi-barbarism 

 individuals had to earn and win their ovpn distinctions. No 

 hereditary surnames were in use among the Mexicans ante- 

 rior to the Spanish conquest. It is stated in a recent treatise 

 on European Heraldry^ that some of the peasants of the 

 Jura Mountains did not possess them so late as the Election 

 of 1789. We learn from the same authorities that surnames 

 did not come into general use in Europe until after the 

 second crusade of 1H7, which gave such an impetus to the 

 bearing of coat armor and heraldic insignia in general. In 

 this regard it is interesting to note that it was to the inter- 

 tribal wars waged in Mexico solely for the purpose of secur- 

 ing human victims for religious sacrifices that we can trace 

 the development of Mexican heraldry. The independent in- 

 vention and use of heraldic insignia in the New World is but 

 another proof of the truth of the dictum that human nature 

 is very much alike all the world over. 

 Brighton, England. 



GAY HEAD. 



BT P. R. UHLEB. 



The steady flow of modern travel has opened an easy way to 

 the delightful island of Martha's Vineyard, where the socially in- 

 clined may enjoy the advantages of summer schools of science, 

 or participate in the exercises of the camp-meeting within spa- 

 cious and airy pavilions. Here the artist finds a prospect of varied 

 color, with long vistas of cliff and sea and sky standing forth in 

 surpassing loveliness and inviting an effort to place on canvas his 

 richest and brightest tints. 



To the student of nature, however, there is access to an ever- 

 increasing store of facts. The more he investigates the structure 

 of the region, with its assemblage of creatures and plants, or 

 views the struggles of atmosphere, land, and ocean to maintain 

 an equilibrium, the more he finds himself beset by perplexing 

 questions, which will not be answered at his bidding. A riddle, 

 as yet but partly solved, lies involved in that wonderful piece of 

 earthy structure called Gay Head. Here, at the western ex- 

 tremity of the island rests a huge pile of sand, rook, and clay, 

 more than one hundred feet high, tinted with numerous vivid 

 colors, which have been the wonder and delight of the voyager 

 ever since the discovery of the country. The sparse settlement of 

 the island has as yet produced but a short chapter of the history 

 of its people ; but the record of nature's changes and disturbances, 

 which have affected the land and sea, would fill large volumes. 



To one series of these changes, belonging to its geology, we 

 would now direct attention. The greater part of the island shows 

 evidences of having been submerged five times beneath the 

 waters. At each emergence from the water, an increased thick- 

 ness was given to the body of the land, so that at the beginning 

 of the last glacial period it stood on the western side at a level of 

 not less than two hundred feet above the surface of the tide. 



At the close of that period and chiefly remaining to the present 

 time, a deep deposit of fine sand, boulders, gravel, and broken 

 stones, from ten to twenty-five feet in thickness, covered the 

 upper slope of the ridge. The Potomac Clay, which forms the 

 inner and also the lowest descending division of the deposits rest- 

 ing here, rises like a central core to near the summit of this hill. 

 As most of the other members below the glacial deposits are 

 either absent from, or only feebly represented on, the upper sur- 

 face of the clay, a thin bed of sand and other glacial material 

 forms the superficial covering. On both slopes of this ridge, the 

 west and the east, the column of geological formations is present, 

 although not in fully unbroken continuity, the Cretaceous Green- 

 Sand Marl having not been found on the eastern slope by the 



1 A Treatise on Heraldry: British and Foreign. By John Woodward, 

 F.S.A., and the late George Burnett, LL.D. (Lyon King at Arms). W. & K. 

 Johnston, Edinburgh, 1891. 



writer. On this side, however, theRaritan Formation, previously 

 defined in Maryland as the Alternate Clay-Sand group, displays an 

 exceedingly fine exposure, with the strata and laminated layers 

 in original order. Here, also, it is enriched with the same plant 

 fossils and lignitic wood so characteristic of these beds on the 

 Raritan, Severn, Magothy, and other rivers of New Jersey and 

 Maryland. 



No evidences of mountain-folding appear in any part of the ele- 

 vated division of the land. The underlying member which de- 

 scends deep below tide, is the Variegated Potomac Claj', and this 

 forms the foundation for all the other formations in their usual 

 order of superposition. 



Deep denudation and erosion followed the completion of the 

 Potomac Clay, and it was cut to below the line of present low tide 

 at the localities now occupied by Menemsha, -Squibnocket and 

 Nashaquitsa ponds. The broken surface of this clay and the 

 presence of the Raritan and other beds above it on the low hills 

 of Menemsha Bight, show how deeply the Potomac formation was 

 here degraded before the next succeeding formation was 

 laid down. Consequently in early Cretaceous time a high plateau 

 of the clay was carved into sloping reliefs which had their most 

 depressed surfaces spreading away towards the east and south. 



The steep side of the island is on the west, and here it is that 

 the modern surf has cut away large tracts of the ancient bluff. 

 On the Gay Head division the sea has been digging away the 

 cliffs at the rate, it is said, of sixteen to twenty feet in a year. 

 The stretch of boulders called the Devil's Bridge, lying at a dis- 

 tance of fully half a mile from the present beach, shows where 

 the outer border of the bluff formerly stood. The Potomac Clay 

 not only extends out that far at the bottom of this shallow shelf 

 of Vineyard Sound, but we are told that it sticks to the anchor in 

 the channel which now runs on a course more than two miles 

 distant from the present beach. A searching survey ought to 

 show that this clay imderlies the Elizabeth Islands and stretching 

 away south-west passes under the borders of the mainland of 

 Massachusetts and Rhode Island, and from thence under Long 

 Island and Staten Island to beneath the lower clays of New Jer- 

 sey. 



The section as it is now exposed in the less-disturbed bluffs of 

 Gay Head shows the Variegated Clay near the beach in strata or 

 ai-ched beds from three to more than ninety feet in thickness. 

 The undisturbed upper part of this member is sometimes a whitish 

 or red clay, and is often more or less mixed with sand. 



Immediately above this, but not on the summit of the clay, 

 rests the group for which we now offer the name Raritan Forma- 

 tion, from the river on the shores of which it is so extensively ex- 

 posed. It consists of a few feet of brown, coarse sand at base, 

 which is sometimes indurated Jnto a moderately coherent sand- 

 stone. Above this is a bed, two or three feet thick, of white 

 sand locally streaked with white clay. Over this the laminated 

 sands, black and gray, charged with lignite, and parted with fine 

 white sand, rise up into thin layers of a paler clay which alter- 

 nates with seams of the white sand. This clay appears more 

 massive in some sections of the bluffs, and occasionally forms a 

 homogeneous stratum, from three to five feet thick. Next above 

 this is a most conspicuous stratum of disintegrated granite, 

 which is a kind of coarse rock-flour, wliite on the weathered sur- 

 face, but gray in the covered mass. It forms a bed ranging from 

 ten to more than fifteen feet in thickness. This forms the su- 

 perior member of the group, while the whole Raritan Formation, 

 as here recognized, reaches a maximum thickness of about fifty 

 feet. 



Next higher in the bluffs rest the ferruginated remnants of the 

 Cretaceous Green-Sand Marl. The great body of this deposit has 

 slipped down or been overthrown upon the steep side of the cliff 

 facing Vineyard Sound. It appears in three separate piles, stretch- 

 ing from near the summit of the projecting buttresses down to 

 the beach. The only part of it now remaining near the line of 

 its original position is represented by a few inches of altered 

 brown sand, in patches. These are the vestiges of the thin edge 

 of the stratum which stretched out towards the sound, and which 

 terminated in a bed eight to ten feet thick in modern time. 

 Eighty or more feet outwards it is a thick body of dark-green 



