with a shower of hail. After the 23d the air was remarkably cold, the lowest point reached by the mercury being 29°, on the morning of the 24th. At noon it was 41°, with ice in the shade all day. After this, it was at or below the freezing point on five mornings, and during the last week of the month the ground continued frozen in the shade. In December 1850 the thermometer fell to 28°, and in January 1854 to 25°, but the last eight days of December 1855 had a lower mean temperature than any other similar period since the commencement of my observations in 1850. The mountains of the Coast Range in the southeast were seen covered with snow, and snow fell to a great depth in the northern counties.

Summary for the year 1855.-The mean temperature of the whole year was as follows: at sunrise, 50°-771, at 9 A. M. 570.563, at noon 640 368, at 10 p. м. 520.916. The mean of the extremes, which represents the temperature of the year, was 570-57, which coincides, it may be said precisely, with the mean temperature at 9 A. M. This appears to be nearly the mean temperature of our climate, as the following figures for five years will show:

Mean temperature of 1851, 560 573

December was not only the coldest month in the year, but the coldest within the range of my record, which extends back to the winter of 1850-51. The month of January, 1854, comes next in order, and then December, 1850. After the middle of January, the sun acquires sufficient power to raise the temperature very materially. Hence February is never a cold month, and April is sometimes as warm as July. The autumn months are the warmest of the year, the cold sea breeze at that season declining in force. In 1855, the warmest month was August; next comes September, then October, then July, then June, and then March.

The extreme heat of the year was 90°. The mercury has at no time in the course of my observations reached this elevation, except in September, 1852, when it stood at 970 and 98° respectively on two consecutive days. In the whole interior of the state, beyond the immediate influence of the ocean winds, this is a common temperature, and indeed much below the extreme heat of summer. Whenever such weather occurs at San Francisco, it is by a suspension of the ordinary programme, the sea-breeze holding off and allowing the climate of the interior to invade its domain. In some years the extreme heat at San Francisco is not

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above 84°. To what extent we are wont to suffer from heat in this latitude of 37 degrees, may be determined from the fact that in the year 1855, the mercury rose to 80° or above, only on six days. In 1851 it reached that point on nine days, in 1852 on fourteen days, in 1853 on eleven days, and in 1854 on twelve days. More than one half of these warm days were in the autumn, and less than one third in the summer months.

The greatest degree of cold in 1855, was 29°, and the mercury was at or below the freezing point on six days, all of which were in December. It was below 40 on ten days, three of which were in January, and seven in December. In some winters there is no freezing weather, and the most tender plants may bloom in the gardens from season to season. The lowest temperature on my record is 250,-in January 1854. Next to this 28°, in December 1850, and next, 29° in December 1855. In the year 1853 the mercury did not fall below 40°. The whole number of freezing mornings in 1850 was two, in 1851 one, in 1852 none, in 1853 none, in 1854 three, in 1855 six. The coldest noonday in 1855 was 41°. In December 1850 there was one day when the noon temperature was 38°, and in January 1854, a day when it rose no higher than 37°. Such weather however is extraordinary, and when it occurs every body declares the like was never before known, and that the climate is changing in deference to the American population.

The warmest morning in the year was 64°. The warmest morning for the last five years was 66°. There are but one or two mornings in the year which approach this figure. A sultry night is unheard of. A single night that could be called warm has happened in five years, and then the thermometer was 76° at 10 P. M. and 66° next morning.

The range of the thermometer in 1855 was 61°. In 1851 the range was 54°; in 1852, 63°; in 1853 48°; in 1854, 62°.

The greatest barometric pressure in the year was 30-16 in., the lowest 29-40 in. Range 0-76 in.,-which is nearly the mean range for a series of years. The lowest point reached in five years was 29-20 in.,-during a violent southerly storm.

The time occupied by the various winds is thus represented: Land winds, NW 33 days.

SE 16 days.
S 48 66

Sea winds,

W 204

It may be well to explain that the northwest and southeast winds blow in a line with the coast, and are classed, the former as land winds and the latter as sea winds, not so much from their direction as their sensible qualities.

Total, rain on 66 days, 27.80 in.,-which is a larger quantity than common, as the following statement will show.

Comparing one rainy season with another, a greater difference appears. The winter of 1850-51 furnished but 7.31 in., that of 51-52, 18.00 in., that of 52-53, 33-46 in., that of 53-54, 22-93 in., and that of 54-55, 24-10 in.

There was some hail in January, and again in December, but no snow. For a few days in each of these months the Coast Mountains in the SE were seen to be covered with snow.

The clouds were sensibly electrified five times-twice in April, once in August, once in September, and once in December. The lightning or thunder was distinct except in December when there was a regular thunder-gust with heavy thunder.

On the evenings of the 11th and 12th of August shooting stars were numerous, and still more so on the evening of December 11th. Nothing extraordinary was observed in November, about the anniversary of the great meteoric shower in 1833.

ART. XXXII.-On the Geology of the Hudson's Bay Territories, and of portions of the Arctic and Northwestern Regions of America by A. K. ISBISTER, M.A., M.R.C.P. &c.

IN submitting to the society a Geological map of this extensive region, with a few explanatory remarks, my object has been to recapitulate very concisely the various observations of the geologists and travellers who have explored, and of the naturalists who have examined the organic remains of this portion of the American Continent, and to present as completely as possible the results which have been hitherto attained in the study of its geological formations. The numberless difficulties inherent in such an undertaking, embracing a range of country so vast and so difficult to explore, or even to obtain access to, must necessarily render any attempt of this nature very imperfect; but I have been * Quart. Jour. Geol. Soc., xi, p. 497, London, 1855. [We omit the map.—EDs.] SECOND SERIES, Vol. XXI, No. 63.—May, 1856.

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induced to undertake it in the belief that, in the absence of any general view of the geological structure of this extensive but interesting region, even the most cursory classification of its formations might be useful to those employed in developing the structure of the crust of the earth, the more especially as it is not probable that the attention of practical geologists will soon be directed to this distant and almost inaccessible field of investigation.

To render the present attempt as complete as the state of our knowledge will admit, I have carefully studied all the published documents and the geological collections relating to the subject to which I have been able to obtain access. And I have myself resided for many years in various parts of the territory, which I may add, I have traversed from one extremity to the other,from the borders of the United States to the Arctic Ocean in one direction, and from the frontiers of Russian America to Hudson's Bay in the other.

The titles of the publications to which I have referred are indicated below, and may be considered as presenting a bibliographical view of what is known of the geology of this part of America.

LIST OF WORKS RELATING TO THE GEOLOGY OF THE NORTHERN PART OF NORTH AMERICA.

Northwest Coast and Russian America.

Geology of the United States Exploring Expedition under the command of Commodore Wilkes. By JAMES D. DANA. New York, 1850.

Geological Appendix to Captain Beechey's Voyage to Behring's Straits in the ship "Blossom." By Dr. BUCKLAND. London, 1839.

Beitrag zur Kenntniss der orographischen und geognostischen Beschaffenheit der Nord-West Küste Amerika's. Von Dr. C. GRENWINGK. St. Petersburg, 1850.

Exploration and Survey of Peel's River; a portion of the chain of the Rocky Mountains and the country west of McKenzie's River. By A. K. ISBISTER. Journal of the Royal Geographical Society for 1846.

Hudson's Bay Territories and Arctic Regions.

Topographical and Geological Appendices to the Narratives of Sir John Franklin's First and Second Journeys to the Shores of the Polar Sea. By Dr. RICHARDSON. And Note on the Fossils. By Prof. JAMESON. London, 1825 and 1828.

Observations on the Rock Specimens collected during the First Polar Voyage of Captain Parry. By CHARLES KÖNIG. London, 1824.

Notes on the Geology of the Countries discovered during Captain Parry's Second and Third Expeditions. By Prof JAMESON. London, 1826.

Geological Appendix to the Narrative of an Attempt to reach the North Pole by Sir Edward Parry, in the year 1827. By Professor JAMESON. London, 1828.

Geological Appendix to Dr. Scoresby's "Journal of a Voyage to the Northern Whale Fishery, including Researches and Discoveries on the East Coast of Grenland." By Professor JAMESON. Edinburgh, 1823.

Discovery and Adventure in the Polar Seas and Regions: Edinburgh Cabinet Library; with a Chapter on Arctic Geology. By Sir JOHN LESLIE, Professor JAMESON, and HUGH MURRAY. 1832.

Voyage of Discovery for Exploring Baffin's Bay. By J. Ross. 1819. Appendix on the Rock-specimens. By Dr. M'CULLOCH.

Journal of Captain Penny's Voyage to Baffin's Bay and Barrow's Straits, in search of Sir John Franklin. By Dr. P. C. SUTHERLAND. With an Appendix on Geology. By J. W. SALTER. London, 1852.

Arctic Silurian Fossils. By J. W. SALTER. 1853. Quart. Journ. Geol. Soc. vol. ix. On the Geological and Glacial Phænomena of the Coasts of Davis's Straits and Baffin's Bay. By P. C. SUTHERLAND, M.D. 1853. Quart. Journ. Geol. Soc. vol. ix. RINK, H., Geology of West Greenland. Trans. Roy. Soc. Denmark, 1852. (Om den geographiske Beskaffenhed af de Danske Handelsdistriker i Nordgrönland.)

STEINHAUER on the Geology of Labrador. 1814. Trans. Geol. Soc. vol. ii. BAYFIELD, on the Geology of the N. Coast of the St. Lawrence. 1887. Trans. Geol. Soc. 2nd Series, vol. v.

On the Geology of Lake Huron. By Dr. BIGSBY. 1824. Trans. Geol. Soc. 2nd Series, vol. i.

On the Geology of the Lake of the Woods [and Bainy River]. By Dr. BIGSBY. 1852. Quart. Journ. Geol. Soc. Vol. viii.

On the Geology of Rainy Lake, South Hudson's Bay. By Dr. BIGSBY. 1854. Quart. Journ. Geol. Soc. vol. x.

On the Drift of the Lake of the Woods and South Hudson's Bay. By Dr. BIGSBY. 1851. Quart. Journ. Geol. Soc. vol. vii.

Narrative of the Arctic Land Expedition to the Mouth of the Great Fish River. By Captain BACK, R.N. Appendix on Geology. By W. H. FITTON, M.D. London, 1836.

Journal of a Boat Voyage through Rupert's Land and the Arctic Sea, in search of the Discovery Ships under Sir. John Franklin. By Sir. JOHN RICHARDSON, London, 1851.

On some points of the Physical Geography of North America. By Sir. J. RICHARDSON. 1851. Quart. Journ. Geol. Soc. vol. vii.

Report of a Geological Survey of Wisconsin, Iowa, and Minnesota, and incidentally of a portion of Nebraska Territory [including the Red River of Lake Winnipeg]. By DAVID DALE OWEN. Philadelphia, 1852.

The chief sources of information, however, on which I have relied in confirmation of my own observations are the valuable Memoirs of Mr. Salter on Arctic Silurian Fossils, published in the Quarterly Journal of the Geological Society, vol. ix, and in the Appendix to Dr. Sutherland's Journal of Capt. Penny's Voyage, and the extensive researches and the numerous able publications of the great Arctic traveller Sir John Richardson, to whom science is indebted for nearly all that is known of the natural history of the vast region surrounding Hudson's Bay.

The collections of rock-specimens and minerals brought to England by the expeditions of discovery through this territory, to which Sir John Richardson was attached, and the various Arctic expeditions by which its northern shores have been traced, as well as by those recently engaged in the search for Sir John Franklin, are very extensive, and throw much valuable light on the mineral structure of the various formations which prevail in the northern regions of America. It was not, however, until within the last few years that any considerable collection had been made of the organic remains belonging to these formations, by which alone their relative ages and their true characters can be determined. Some of the fossil remains alluded to have been described and figured by Mr. Salter in the papers already referred to, others by Dr. Dale Owen, of the U. S. Geological Survey, Dr. Buckland and others; and some (as will be subsequently noticed) have been described, though only incidentally and in general terms, by Sir John Richardson, Mr. Sowerby, the late Mr. König