Advice: Trees for shallow soil over chalk
Chalk soils have a very high lime content so can be harmful to many trees.
That being said, calcium and magnesium limestone in the wild supports a very diverse range of plants so the gardener need not be entirely defeated by theses conditions. Chalk is more difficult when there is only a shallow layer of soil above the rock since this leads to soil drying out quickly. Attempts to fight nature by planting your favourites will almost certainly fail. The best advice is to go with the flow by choosing from the list below of varieties known to be happy in these situations.
Acer......................................campestre
Acer.....................negundo and cultivars
Acer.................platanoides and cultivars
Acer...........pseudoplatanus and cultivars
Aesculus.........................................(all)
Caragana.........arborescens and cultivars
Carpinus.................betulus and cultivars
Cercis.................................siliquastrum
Cornus.......................mas and cultivars
Cotoneaster....................................(all)
Crataegus.......................................(all)
Euonymus.......................................(all)
Fagus...................sylvatica and cultivars
Forsythia..........................................(all)
Fraxinus...............excelsior and cultivars
Prunus.......................Japanese cherries
Sambucus.......................................(all)
Sorbus.........................aria and cultivars
Sorbus....................hybrida and cultivars
Syringa...........................................(all)
Taxus....................baccata and cultivars
Thuja..........................................plicata