CLIMATE AND SOIL. The climate of Maryland is one of transition in which the northern frozen winter gives way to the open southern win ter. The extreme temperatures of more northern locations are occasionally met with, but the periods of cold are of less duration and the num ber of freezing days and the amqunt of snowfall are less. An extreme winter temperature of 26° below zero has been recorded at Sunnyside in the Alleghany Plateau and a summer temperature of 109° F. near Cumberland. Changes of tempera ture are frequent, and there is a great daily range. In north central 'Maryland the average temperature for January is 30° ; that for July e5°. The average annual temperature for the State is between 53° and 54°. The average dates for first and last killing frosts in the plateau are October 1st and April 15th; on the Marine Islands the growing season is a month longer, extending from April 1st to October 15th.
The average rainfall for the State is 43 inches, of which 11.5 to 12 fall in spring and in summer and 9.5 to 10 in the fall and in winter. The effects of elevation and slope are clearly shown in the distribution of the rainfall. The western slope of the Allegheny Plateau receives 53 inches; the eastern slope of Parr's Ridge over 45; the inclosed valleys between Cumberland and Hagerstown and small sections at the ex treme east and southwest of the State receive between 30 and 35. The Atlantic Plain in the main receives from 42 to 48 inches. The snowfall averages 25.4 inches for the State, 16.6 for the southern and 43.4 for the west ern districts. The number of days of precipi tation on the coast is 130, in the mountains 140. The relative humidity varies from 80 in the sea islands to 65 at, the extreme west. The climate is everywhere suitable to tree growth; hard woods, especially oak and hickory, predominate. The warm moist climate and light soil of the eastern shore cause that district to be the home of many southern plants not found else where in the same latitude.
Maryland has a variety of soils corresponding with the geological formations. The more re cent formations of the Atlantic Plain have light, sandy and loamy soils, unsuited to grass, but especially adapted to vegetables, truck-farming, small fruits, and peaches. The region of meta morphic rocks and the limestone and shale val leys of the west are of heavier, often clay. soils.
usually very fertile and adapted to wheat, maize, grass, and clover. On the western• slope of the Blue Ridge Mountains, the Cambrian (Harper's) shale, crossing the State from Harper's Ferry northeastward, produces a strip of sandy, shaly soil with exceptional adaptation to peaches, which are here a highly specialized crop. Sim ilar shaly soils are on the flanks of all the ranges.
and the valley floors are usually Maryland presents a great variety of geologic formations. owing to the fact that the various outcrops which run in broad bands parallel with the Atlantic coast are here so nar row that the whole series is encompassed by the State, from the coastal plain formation to the western coal fields, while farther south they widen out so that even the State of North Caro lina does not include them all. The entire por tion of the State east of Chesapeake Bay and a strip from 5 to 20 miles wide along its west ern shore are covered with the recent unindurated coastal plain formation. consisting of Tertiary sands and clays east of the bay, and chiefly Cre taceous, with some Eocene deposits, on the west ern shore. \Vest of this follows the Arch:eau belt of the Piedmont Plain. It is here about 50 miles broad, occupying the whole central part of the State, hut in early Mesozoic time this Archaean land was divided into two parts by a narrow arm of the sea running southwestward from the present mouth of the Hudson, and whose bed is now filled with a deep layer of Triassic red sandstone occupying the Frederick Valley. The narrow western part of the State is traversed by the various outcrops brought to the surface by the Appalachian upheaval and subsequent denudation. They are chiefly Devo nian and Silurian strata, more or less tilted and covered in the extreme west by the carboniferous formation. In addition to these there are intru sions of eruptive rocks running in a chain of dikes east of the Blue Ridge. During the Eocene and Pleistocene periods the eastern part of the State was subjected to repeated changes of level, whose net result was the formation of a system of river valleys and their partial submergence into Chesapeake Bay and its branehing estu aries.